The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

The Diagnosis: Cystic Neutrophilic Granulomatous Mastitis

The histopathologic findings in our patient were characteristic of cystic neutrophilic granulomatous mastitis (CNGM), a rare granulomatous mastitis associated with Corynebacterium and suppurative lipogranulomas. Although not seen in our patient, the lipid vacuoles may contain gram-positive bacilli.¹ The surrounding mixed inflammatory infiltrate contains Langerhans giant cells, lymphocytes, and neutrophils. Cystic neutrophilic granulomatous mastitis is seen in parous women of reproductive age. Physical examination demonstrates a palpable painful mass on the breast. Wound cultures frequently are negative, likely due to difficulty culturing Corynebacterium and prophylactic antibiotic treatment. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. The diagnosis of CNGM often is missed or delayed due to its rarity and many potential mimickers. Clinically, CNGM may be virtually impossible to discern from invasive carcinoma.¹

Our patient was treated with vancomycin and cefepime with incision and drainage as an inpatient. Upon discharge, she was started on prednisone 1 mg/kg daily tapered by 10 mg every 5 days over 1 month and doxycycline 100 mg twice daily. She was then transitioned to topical hydrocortisone and bacitracin; she reported decreased swelling and pain. No new lesions formed after the initiation of therapy; however, most lesions remained open. Cystic neutrophilic granulomatous mastitis remains a challenging entity to treat, with a variable response rate reported in the literature for antibiotics such as doxycycline and systemic and topical steroids as well as immunosuppressants including methotrexate.^2,3

Cystic neutrophilic granulomatous mastitis can be distinguished from hidradenitis suppurativa clinically because ulcerating lesions can involve the superior portions of the breast in CNGM, whereas hidradenitis suppurativa typically is restricted to the lower intertriginous parts of the breast. Other mimics of CNGM can be distinguished with biopsy. Histology of pyoderma gangrenosum lacks prominent granuloma formation. Although sarcoidosis and mycobacterial infection show prominent granulomas, neither show the characteristic lipogranulomas seen in CNGM. Additionally, the granulomas of sarcoidosis are much larger and deeper than CNGM. Mycobacterial granulomas also typically reveal bacilli with acid-fast bacilli staining or via wound culture.

Female-pattern hair loss (FPHL) was identified in 52% of postmenopausal women, and 4% of these cases involved extensive baldness, based on data from 178 individuals.

FPHL can develop at any time from teenage years through and beyond menopause, wrote Sukanya Chaikittisilpa, MD, of Chulalongkorn University, Bangkok, and colleagues.

The cause of FPHL remains uncertain, but the presence of estrogen receptors in hair follicles suggests that the hormone changes of menopause may affect hair growth, the researchers said.

In a study published in Menopause, the researchers evaluated 178 postmenopausal women aged 50-65 years for FPHL. FPLH was determined based on photographs and on measures of hormone levels, hair density, and hair diameter.

The overall prevalence of FPHL was 52.2%. The hair loss was divided into three categories indicating mild, moderate, and severe (Ludwig grades I, II, and III) with prevalence of 73.2%, 22.6%, and 4.3%, respectively. The prevalence of FPHL also increased with age and time since menopause. In a simple logistic regression analysis, age 56 years and older and more than 6 years since menopause were significantly associated with FPHL (odds ratios, 3.41 and 1.98, respectively).

However, after adjustment for multiple variables, only a body mass index of 25 kg/m² or higher also was associated with increased prevalence of FPHL (adjusted OR, 2.65).

A total of 60% of the study participants met criteria for low self-esteem, including all the women in the severe hair loss category.

“The postmenopausal women with FPHL in our cohort had lower total hair density, terminal hair density, hair thickness, hair unit density, and average hair per unit than those with normal hair patterns,” although vellus hair density was higher in women with FPHL, the researchers wrote in their discussion of the findings. This distinction may be caused in part by the shortened hair cycle and reduced anagen phase of velluslike follicles, they said.

The study findings were limited by several factors, including the cross-sectional design and the inclusion of only women from a single menopause clinic, which may not reflect FPHL in the general population, as well as the reliance on patients’ recall, the researchers noted. Another limitation was the inability to assess postmenopausal hormone levels, they added.

However, “This study may be the first FPHL study conducted in a menopause clinic that targeted only healthy postmenopausal women,” they wrote. More research is needed to determine the potential role of estrogen and testosterone on FPHL in postmenopausal women, and whether a history of polycystic ovarian syndrome has an effect, they said. Meanwhile, current study results may help clinicians and patients determine the most appropriate menopausal hormone therapies for postmenopausal women with FPHL, they concluded.
 

Consider lifestyle and self-esteem issues

The current study is important at this time because a larger proportion of women are either reaching menopause or are menopausal, said Constance Bohon, MD, a gynecologist in private practice in Washington, in an interview.

“Whatever we in the medical community can do to help women transition into the menopausal years with the least anxiety is important,” including helping women feel comfortable about their appearance, she said.

“For women in the peri- and postmenopausal years, hair loss is a relatively common concern,” Dr. Bohon said. However, in the current study, “I was surprised that it was associated with low self-esteem and obesity,” she noted. “For these women, it would be interesting to know whether they also had concerns about the appearance of their bodies, or just their hair loss,” she said. The question is whether the hair loss in and of itself caused low self-esteem in the study population, or whether it exacerbated their already poor self-assessment, Dr. Bohon said. “Another consideration is that perhaps these women were already feeling the effects of aging and were trying to change their appearance by using hair dyes, and now they find themselves losing hair as well,” she noted.

The takeaway message for clinicians is that discussions with perimenopausal and postmenopausal women should include the topic of hair loss along with hot flashes and night sweats, said Dr. Bohon.

Women who are experiencing hair loss or concerned about the possibility of hair loss should ask their doctors about possible interventions that may mitigate or prevent further hair loss, she said.

As for additional research, “the most important issue is to determine the factors that are associated with hair loss in the perimenopausal and postmenopausal years,” Dr. Bohon said. Research questions should include impact of dyeing or straightening hair on the likelihood of hair loss, and whether women with more severe hot flashes/night sweats and/or sleeplessness have more hair loss than women who do not experience any of the symptoms as they go through menopause, she emphasized.

Other considerations are whether certain diets or foods are more common among women who have more hair loss, and whether weight loss into a normal range or weight gain into a body mass index greater than 25 kg/m² affects hair loss, said Dr. Bohon. Also, don’t discount the impact of stress, and whether women who have lost hair identify certain stressful times that preceded their hair loss, as well as what medications could be associated with hair loss, and whether hormone therapy might prevent hair loss, she said.

The study was supported by the Ratchadapiseksompotch Fund, Faculty of Medicine, Chulalongkorn University. The researchers had no financial conflicts to disclose. Dr. Bohon had no financial conflicts to disclose and serves on the Editorial Advisory Board of Ob.Gyn. News.

Female-pattern hair loss (FPHL) was identified in 52% of postmenopausal women, and 4% of these cases involved extensive baldness, based on data from 178 individuals.

FPHL can develop at any time from teenage years through and beyond menopause, wrote Sukanya Chaikittisilpa, MD, of Chulalongkorn University, Bangkok, and colleagues.

The cause of FPHL remains uncertain, but the presence of estrogen receptors in hair follicles suggests that the hormone changes of menopause may affect hair growth, the researchers said.

In a study published in Menopause, the researchers evaluated 178 postmenopausal women aged 50-65 years for FPHL. FPLH was determined based on photographs and on measures of hormone levels, hair density, and hair diameter.

The overall prevalence of FPHL was 52.2%. The hair loss was divided into three categories indicating mild, moderate, and severe (Ludwig grades I, II, and III) with prevalence of 73.2%, 22.6%, and 4.3%, respectively. The prevalence of FPHL also increased with age and time since menopause. In a simple logistic regression analysis, age 56 years and older and more than 6 years since menopause were significantly associated with FPHL (odds ratios, 3.41 and 1.98, respectively).

However, after adjustment for multiple variables, only a body mass index of 25 kg/m² or higher also was associated with increased prevalence of FPHL (adjusted OR, 2.65).

A total of 60% of the study participants met criteria for low self-esteem, including all the women in the severe hair loss category.

“The postmenopausal women with FPHL in our cohort had lower total hair density, terminal hair density, hair thickness, hair unit density, and average hair per unit than those with normal hair patterns,” although vellus hair density was higher in women with FPHL, the researchers wrote in their discussion of the findings. This distinction may be caused in part by the shortened hair cycle and reduced anagen phase of velluslike follicles, they said.

The study findings were limited by several factors, including the cross-sectional design and the inclusion of only women from a single menopause clinic, which may not reflect FPHL in the general population, as well as the reliance on patients’ recall, the researchers noted. Another limitation was the inability to assess postmenopausal hormone levels, they added.

However, “This study may be the first FPHL study conducted in a menopause clinic that targeted only healthy postmenopausal women,” they wrote. More research is needed to determine the potential role of estrogen and testosterone on FPHL in postmenopausal women, and whether a history of polycystic ovarian syndrome has an effect, they said. Meanwhile, current study results may help clinicians and patients determine the most appropriate menopausal hormone therapies for postmenopausal women with FPHL, they concluded.
 

Consider lifestyle and self-esteem issues

The current study is important at this time because a larger proportion of women are either reaching menopause or are menopausal, said Constance Bohon, MD, a gynecologist in private practice in Washington, in an interview.

“Whatever we in the medical community can do to help women transition into the menopausal years with the least anxiety is important,” including helping women feel comfortable about their appearance, she said.

“For women in the peri- and postmenopausal years, hair loss is a relatively common concern,” Dr. Bohon said. However, in the current study, “I was surprised that it was associated with low self-esteem and obesity,” she noted. “For these women, it would be interesting to know whether they also had concerns about the appearance of their bodies, or just their hair loss,” she said. The question is whether the hair loss in and of itself caused low self-esteem in the study population, or whether it exacerbated their already poor self-assessment, Dr. Bohon said. “Another consideration is that perhaps these women were already feeling the effects of aging and were trying to change their appearance by using hair dyes, and now they find themselves losing hair as well,” she noted.

The takeaway message for clinicians is that discussions with perimenopausal and postmenopausal women should include the topic of hair loss along with hot flashes and night sweats, said Dr. Bohon.

Women who are experiencing hair loss or concerned about the possibility of hair loss should ask their doctors about possible interventions that may mitigate or prevent further hair loss, she said.

As for additional research, “the most important issue is to determine the factors that are associated with hair loss in the perimenopausal and postmenopausal years,” Dr. Bohon said. Research questions should include impact of dyeing or straightening hair on the likelihood of hair loss, and whether women with more severe hot flashes/night sweats and/or sleeplessness have more hair loss than women who do not experience any of the symptoms as they go through menopause, she emphasized.

Other considerations are whether certain diets or foods are more common among women who have more hair loss, and whether weight loss into a normal range or weight gain into a body mass index greater than 25 kg/m² affects hair loss, said Dr. Bohon. Also, don’t discount the impact of stress, and whether women who have lost hair identify certain stressful times that preceded their hair loss, as well as what medications could be associated with hair loss, and whether hormone therapy might prevent hair loss, she said.

The study was supported by the Ratchadapiseksompotch Fund, Faculty of Medicine, Chulalongkorn University. The researchers had no financial conflicts to disclose. Dr. Bohon had no financial conflicts to disclose and serves on the Editorial Advisory Board of Ob.Gyn. News.

Female-pattern hair loss (FPHL) was identified in 52% of postmenopausal women, and 4% of these cases involved extensive baldness, based on data from 178 individuals.

FPHL can develop at any time from teenage years through and beyond menopause, wrote Sukanya Chaikittisilpa, MD, of Chulalongkorn University, Bangkok, and colleagues.

The cause of FPHL remains uncertain, but the presence of estrogen receptors in hair follicles suggests that the hormone changes of menopause may affect hair growth, the researchers said.

In a study published in Menopause, the researchers evaluated 178 postmenopausal women aged 50-65 years for FPHL. FPLH was determined based on photographs and on measures of hormone levels, hair density, and hair diameter.

The overall prevalence of FPHL was 52.2%. The hair loss was divided into three categories indicating mild, moderate, and severe (Ludwig grades I, II, and III) with prevalence of 73.2%, 22.6%, and 4.3%, respectively. The prevalence of FPHL also increased with age and time since menopause. In a simple logistic regression analysis, age 56 years and older and more than 6 years since menopause were significantly associated with FPHL (odds ratios, 3.41 and 1.98, respectively).

However, after adjustment for multiple variables, only a body mass index of 25 kg/m² or higher also was associated with increased prevalence of FPHL (adjusted OR, 2.65).

A total of 60% of the study participants met criteria for low self-esteem, including all the women in the severe hair loss category.

“The postmenopausal women with FPHL in our cohort had lower total hair density, terminal hair density, hair thickness, hair unit density, and average hair per unit than those with normal hair patterns,” although vellus hair density was higher in women with FPHL, the researchers wrote in their discussion of the findings. This distinction may be caused in part by the shortened hair cycle and reduced anagen phase of velluslike follicles, they said.

The study findings were limited by several factors, including the cross-sectional design and the inclusion of only women from a single menopause clinic, which may not reflect FPHL in the general population, as well as the reliance on patients’ recall, the researchers noted. Another limitation was the inability to assess postmenopausal hormone levels, they added.

However, “This study may be the first FPHL study conducted in a menopause clinic that targeted only healthy postmenopausal women,” they wrote. More research is needed to determine the potential role of estrogen and testosterone on FPHL in postmenopausal women, and whether a history of polycystic ovarian syndrome has an effect, they said. Meanwhile, current study results may help clinicians and patients determine the most appropriate menopausal hormone therapies for postmenopausal women with FPHL, they concluded.
 

Consider lifestyle and self-esteem issues

The current study is important at this time because a larger proportion of women are either reaching menopause or are menopausal, said Constance Bohon, MD, a gynecologist in private practice in Washington, in an interview.

“Whatever we in the medical community can do to help women transition into the menopausal years with the least anxiety is important,” including helping women feel comfortable about their appearance, she said.

“For women in the peri- and postmenopausal years, hair loss is a relatively common concern,” Dr. Bohon said. However, in the current study, “I was surprised that it was associated with low self-esteem and obesity,” she noted. “For these women, it would be interesting to know whether they also had concerns about the appearance of their bodies, or just their hair loss,” she said. The question is whether the hair loss in and of itself caused low self-esteem in the study population, or whether it exacerbated their already poor self-assessment, Dr. Bohon said. “Another consideration is that perhaps these women were already feeling the effects of aging and were trying to change their appearance by using hair dyes, and now they find themselves losing hair as well,” she noted.

The takeaway message for clinicians is that discussions with perimenopausal and postmenopausal women should include the topic of hair loss along with hot flashes and night sweats, said Dr. Bohon.

Women who are experiencing hair loss or concerned about the possibility of hair loss should ask their doctors about possible interventions that may mitigate or prevent further hair loss, she said.

As for additional research, “the most important issue is to determine the factors that are associated with hair loss in the perimenopausal and postmenopausal years,” Dr. Bohon said. Research questions should include impact of dyeing or straightening hair on the likelihood of hair loss, and whether women with more severe hot flashes/night sweats and/or sleeplessness have more hair loss than women who do not experience any of the symptoms as they go through menopause, she emphasized.

Other considerations are whether certain diets or foods are more common among women who have more hair loss, and whether weight loss into a normal range or weight gain into a body mass index greater than 25 kg/m² affects hair loss, said Dr. Bohon. Also, don’t discount the impact of stress, and whether women who have lost hair identify certain stressful times that preceded their hair loss, as well as what medications could be associated with hair loss, and whether hormone therapy might prevent hair loss, she said.

The study was supported by the Ratchadapiseksompotch Fund, Faculty of Medicine, Chulalongkorn University. The researchers had no financial conflicts to disclose. Dr. Bohon had no financial conflicts to disclose and serves on the Editorial Advisory Board of Ob.Gyn. News.

The U.S. Food and Drug Administration has approved nivolumab for neoadjuvant treatment of non–small cell lung cancer (NSCLC) in combination with platinum-doublet chemotherapy, regardless of PDL-1 status.

Nivolumab is the first immune checkpoint inhibitor to be approved for resectable NSCLC; its three prior NSCLC indications are for metastatic disease, the agency said in its announcement. 

Approval was based on the CheckMate 816 trial, which randomized 358 patients evenly to either nivolumab plus platinum doublets or to platinum doublets alone every 3 weeks for up to 3 cycles.

Trial participants had histologically confirmed stage IB, II, or IIIA disease, which was measurable by RECIST criteria. They were enrolled regardless of tumor PD-L1 status.

At surgery, the pathologic complete response rate was 24% in the nivolumab arm versus 2.2% in the chemotherapy-alone group.

Median event-free survival was 31.6 months with nivolumab but 20.8 months without it, which translated to a 37% reduction in the risk for progression, recurrence, or death following surgery. A trend toward better overall survival was not statistically significant, Bristol Myers Squibb said in its own announcement.

Nivolumab’s new neoadjuvant indication is for adult patients with resectable NSCLC (tumors greater than or equal to 4 cm or node positive). The recommended dosage is 360 mg in combination with platinum-doublet chemotherapy on the same day every 3 weeks for three cycles.

In a press release from Bristol Myers Squibb, CheckMate 816 investigator and Dana-Farber Cancer Institute thoracic oncologist Mark Awad, MD, PhD, called the approval “a turning point in how we treat resectable NSCLC.”

Patients with known EGFR mutations or ALK translocations, grade 2 or higher peripheral neuropathy, active autoimmune disease, or medical conditions requiring systemic immunosuppression were excluded.

There were no fatal adverse events in the nivolumab arm, but 30% of participants had serious adverse events, most commonly pneumonia and vomiting.

The most common side effects across all grades were nausea (38%), constipation (34%), fatigue (26%), decreased appetite (20%), and rash (20%). Surgical complications and hospital lengths were similar between the two study groups.

Rival checkpoint inhibitor pembrolizumab is also being investigated for neoadjuvant NSCLC.

A version of this article first appeared on Medscape.com.

The U.S. Food and Drug Administration has approved nivolumab for neoadjuvant treatment of non–small cell lung cancer (NSCLC) in combination with platinum-doublet chemotherapy, regardless of PDL-1 status.

Nivolumab is the first immune checkpoint inhibitor to be approved for resectable NSCLC; its three prior NSCLC indications are for metastatic disease, the agency said in its announcement. 

Approval was based on the CheckMate 816 trial, which randomized 358 patients evenly to either nivolumab plus platinum doublets or to platinum doublets alone every 3 weeks for up to 3 cycles.

Trial participants had histologically confirmed stage IB, II, or IIIA disease, which was measurable by RECIST criteria. They were enrolled regardless of tumor PD-L1 status.

At surgery, the pathologic complete response rate was 24% in the nivolumab arm versus 2.2% in the chemotherapy-alone group.

Median event-free survival was 31.6 months with nivolumab but 20.8 months without it, which translated to a 37% reduction in the risk for progression, recurrence, or death following surgery. A trend toward better overall survival was not statistically significant, Bristol Myers Squibb said in its own announcement.

Nivolumab’s new neoadjuvant indication is for adult patients with resectable NSCLC (tumors greater than or equal to 4 cm or node positive). The recommended dosage is 360 mg in combination with platinum-doublet chemotherapy on the same day every 3 weeks for three cycles.

In a press release from Bristol Myers Squibb, CheckMate 816 investigator and Dana-Farber Cancer Institute thoracic oncologist Mark Awad, MD, PhD, called the approval “a turning point in how we treat resectable NSCLC.”

Patients with known EGFR mutations or ALK translocations, grade 2 or higher peripheral neuropathy, active autoimmune disease, or medical conditions requiring systemic immunosuppression were excluded.

There were no fatal adverse events in the nivolumab arm, but 30% of participants had serious adverse events, most commonly pneumonia and vomiting.

The most common side effects across all grades were nausea (38%), constipation (34%), fatigue (26%), decreased appetite (20%), and rash (20%). Surgical complications and hospital lengths were similar between the two study groups.

Rival checkpoint inhibitor pembrolizumab is also being investigated for neoadjuvant NSCLC.

A version of this article first appeared on Medscape.com.

The U.S. Food and Drug Administration has approved nivolumab for neoadjuvant treatment of non–small cell lung cancer (NSCLC) in combination with platinum-doublet chemotherapy, regardless of PDL-1 status.

Nivolumab is the first immune checkpoint inhibitor to be approved for resectable NSCLC; its three prior NSCLC indications are for metastatic disease, the agency said in its announcement. 

Approval was based on the CheckMate 816 trial, which randomized 358 patients evenly to either nivolumab plus platinum doublets or to platinum doublets alone every 3 weeks for up to 3 cycles.

Trial participants had histologically confirmed stage IB, II, or IIIA disease, which was measurable by RECIST criteria. They were enrolled regardless of tumor PD-L1 status.

At surgery, the pathologic complete response rate was 24% in the nivolumab arm versus 2.2% in the chemotherapy-alone group.

Median event-free survival was 31.6 months with nivolumab but 20.8 months without it, which translated to a 37% reduction in the risk for progression, recurrence, or death following surgery. A trend toward better overall survival was not statistically significant, Bristol Myers Squibb said in its own announcement.

Nivolumab’s new neoadjuvant indication is for adult patients with resectable NSCLC (tumors greater than or equal to 4 cm or node positive). The recommended dosage is 360 mg in combination with platinum-doublet chemotherapy on the same day every 3 weeks for three cycles.

In a press release from Bristol Myers Squibb, CheckMate 816 investigator and Dana-Farber Cancer Institute thoracic oncologist Mark Awad, MD, PhD, called the approval “a turning point in how we treat resectable NSCLC.”

Patients with known EGFR mutations or ALK translocations, grade 2 or higher peripheral neuropathy, active autoimmune disease, or medical conditions requiring systemic immunosuppression were excluded.

There were no fatal adverse events in the nivolumab arm, but 30% of participants had serious adverse events, most commonly pneumonia and vomiting.

The most common side effects across all grades were nausea (38%), constipation (34%), fatigue (26%), decreased appetite (20%), and rash (20%). Surgical complications and hospital lengths were similar between the two study groups.

Rival checkpoint inhibitor pembrolizumab is also being investigated for neoadjuvant NSCLC.

A version of this article first appeared on Medscape.com.

The Diagnosis: Blastic Plasmacytoid Dendritic Cell Neoplasm

A diagnosis of blastic plasmacytoid dendritic cell neoplasm (BPDCN) was rendered. Subsequent needle core biopsy of a left axillary lymph node as well as bone marrow aspiration and biopsy revealed a similar diffuse blastoid infiltrate with an identical immunophenotype to that in the skin biopsy from the pretibial mass and peripheral blood.

Previously known as blastic natural killer cell leukemia/lymphoma or agranular CD4+/CD56+ hematodermic neoplasm/tumor, BPDCN is a rare, clinically aggressive hematologic malignancy derived from the precursors of plasmacytoid dendritic cells. It often is diagnostically challenging, particularly when presenting at noncutaneous sites and in unusual (young) patient populations.¹ It was included with other myeloid neoplasms in the 2008 World Health Organization classification; however, in the 2017 classification it was categorized as a separate entity. Blastic plasmacytoid dendritic cell neoplasm typically presents in the skin of elderly patients (age range at diagnosis, 61–67 years) with or without bone marrow involvement and systemic dissemination.^1,2 The skin is the most common clinical site of disease in typical cases of BPDCN and often precedes bone marrow involvement. Thus, skin biopsy often is the key to making the diagnosis. Diagnosis of BPDCN may be delayed because of diagnostic pitfalls. Patients usually present with asymptomatic solitary or multiple lesions.^3-5 Blastic plasmacytoid dendritic cell neoplasm can present as an isolated purplish nodule or bruiselike papule or more commonly as disseminated purplish nodules, papules, and macules. Isolated nodules are found on the head and lower limbs and can be more than 10 cm in diameter. Peripheral blood and bone marrow may be minimally involved at presentation but invariably become involved with the progression of disease. Cytopenia can occur at diagnosis and in a minority of severe cases indicates bone marrow failure.^2-6

Skin involvement of BPDCN is thought to be secondary to the expression of skin migration molecules, such as cutaneous lymphocyte-associated antigen, one of the E-selectin ligands, which binds to E-selectin on high endothelial venules. In addition, the local dermal microenvironment of chemokines binding CXCR3, CXCR4, CCR6, or CCR7 present on neoplastic cells possibly leads to skin involvement. The full mechanism underlying the cutaneous tropism is still to be elucidated.^4-7 Infiltration of the oral mucosa is seen in some patients, but it may be underreported. Mucosal disease typically appears similarly to cutaneous disease.

The cutaneous differential diagnosis for BPDCN depends on the clinical presentation, extent of disease spread, and thickness of infiltration. It includes common nonneoplastic diseases such as traumatic ecchymoses; purpuric disorders; extramedullary hematopoiesis; and soft-tissue neoplasms such as angiosarcoma, Kaposi sarcoma, neuroblastoma, and vascular metastases, as well as skin involvement by other hematologic neoplasms. An adequate incisional biopsy rather than a punch or shave biopsy is recommended for diagnosis. Dermatologists should alert the pathologist that BPDCN is in the clinical differential diagnosis when possible so that judicious use of appropriate immunophenotypic markers such as CD123, CD4, CD56, and T-cell leukemia/lymphoma protein 1 will avoid misdiagnosis of this aggressive condition, in addition to excluding acute myeloid leukemia, which also may express 3 of the above markers. However, most cases of acute myeloid leukemia lack terminal deoxynucleotidyl transferase (TdT) and express monocytic and other myeloid markers. Terminal deoxynucleotidyl transferase is positive in approximately one-third of cases of BPDCN, with expression in 10% to 80% of cells.¹

It is important to include BPDCN in the differential diagnosis of immunophenotypically aberrant hematologic tumors. Diffuse large B-cell lymphoma, leg type, accounts for 4% of all primary cutaneous B-cell lymphomas.¹ Compared with BPDCN, diffuse large B-cell lymphoma usually occurs in an older age group and is of B-cell lineage. Morphologically, these neoplasms are composed of a monotonous, diffuse, nonepidermotropic infiltrate of confluent sheets of centroblasts and immunoblasts (Figure 1). They may share immunohistochemical markers of CD79a, multiple myeloma 1, Bcl-2, and Bcl-6; however, they lack plasmacytoid dendritic cell (PDC)– associated antigens such as CD4, CD56, CD123, and T-cell leukemia/lymphoma protein 1.¹

Adult T-cell leukemia/lymphoma is a neoplasm histologically composed of highly pleomorphic medium- to large-sized T cells with an irregular multilobated nuclear contour, so-called flower cells, in the peripheral blood. The nuclear chromatin is coarse and clumped with prominent nucleoli. Blastlike cells with dispersed chromatin are present in variable proportions. Most patients present with widespread lymph node and peripheral blood involvement. Skin is involved in more than half of patients with an epidermal as well as dermal pattern of infiltration (mainly perivascular)(Figure 2). Adult T-cell leukemia/lymphoma is endemic in several regions of the world, and the distribution is closely linked to the prevalence of human T-cell lymphotropic virus type 1 in the population. This neoplasm is of T-cell lineage and may share CD4 but not PDC-associated antigens with BPDCN.¹

Cutaneous involvement by T-cell lymphoblastic leukemia/lymphoma (T-LBL) is a rare occurrence with a frequency of approximately 4.3%.8 T-cell lymphoblastic leukemia/lymphoma usually presents as multiple skin lesions throughout the body. Almost all cutaneous T-LBL cases are seen in association with bone marrow and/or mediastinal, lymph node, or extranodal involvement. Cutaneous T-LBLs present as a diffuse monomorphous infiltrate located in the entire dermis and subcutis without epidermotropism, composed of medium to large blasts with finely dispersed chromatin and relatively prominent nucleoli (Figure 3). Immunophenotyping studies show an immature T-cell immunophenotype, with expression of TdT (usually uniform), CD7, and cytoplasmic CD3 and an absence of PDC-associated antigens.⁸

Primary cutaneous γδ T-cell lymphoma (PCGDTL) is a neoplasm primarily involving the skin. Often rapidly fatal, PCGDTL has a broad clinical spectrum that may include indolent variants—subcutaneous, epidermotropic, and dermal. Patients typically present with nodular lesions that progress to ulceration and necrosis. Early lesions can be confused with erythema nodosum, mycosis fungoides, or infection. Histologically, they show variable epidermotropism as well as dermal and subcutaneous involvement by medium to large cells with coarse clumped chromatin (Figure 4). Large blastic cells with vesicular nuclei and prominent nucleoli are infrequent. In contrast to BPCDN, the neoplastic lymphocytes in dermal and subcutaneous PCGDTL typically are positive for T-cell intracellular antigen-1 and granzyme B with loss of CD4.⁹

At the time of presentation, 27% to 87% of BPDCN patients will have bone marrow involvement, 22% to 28% will have blood involvement, and 6% to 41% will have lymph node involvement.^{1-4,6,7,10,11} The clinical course is aggressive, with a median survival of 10.0 to 19.8 months, irrespective of the initial pattern of disease.¹ Most cases have shown initial response to multiagent chemotherapy, but relapses with subsequent resistance to drugs regularly have been observed. Age has an adverse impact of prognosis. Low TdT expression has been associated with shorter survival.¹ Approximately 10% to 20% of cases of BPDCN are associated with or develop into chronic myelogenous leukemia, myelodysplastic syndrome, or acute myeloid leukemia.^1,4 Pediatric patients have a greater 5-year overall survival rate than older patients, and overall survival worsens with increasing age. The extent of cutaneous involvement and presence of systemic involvement at initial presentation do not seem to be strong predictors of survival.^{1,2,5-7,10-12} In a retrospective analysis of 90 patients, Julia et al¹² found that the type of skin disease did not predict survival. Specifically, the presence of nodular lesions and disseminated skin involvement were not adverse prognostic factors compared with macular lesions limited to 1 or 2 body areas.¹²

The Diagnosis: Blastic Plasmacytoid Dendritic Cell Neoplasm

A diagnosis of blastic plasmacytoid dendritic cell neoplasm (BPDCN) was rendered. Subsequent needle core biopsy of a left axillary lymph node as well as bone marrow aspiration and biopsy revealed a similar diffuse blastoid infiltrate with an identical immunophenotype to that in the skin biopsy from the pretibial mass and peripheral blood.

Previously known as blastic natural killer cell leukemia/lymphoma or agranular CD4+/CD56+ hematodermic neoplasm/tumor, BPDCN is a rare, clinically aggressive hematologic malignancy derived from the precursors of plasmacytoid dendritic cells. It often is diagnostically challenging, particularly when presenting at noncutaneous sites and in unusual (young) patient populations.¹ It was included with other myeloid neoplasms in the 2008 World Health Organization classification; however, in the 2017 classification it was categorized as a separate entity. Blastic plasmacytoid dendritic cell neoplasm typically presents in the skin of elderly patients (age range at diagnosis, 61–67 years) with or without bone marrow involvement and systemic dissemination.^1,2 The skin is the most common clinical site of disease in typical cases of BPDCN and often precedes bone marrow involvement. Thus, skin biopsy often is the key to making the diagnosis. Diagnosis of BPDCN may be delayed because of diagnostic pitfalls. Patients usually present with asymptomatic solitary or multiple lesions.^3-5 Blastic plasmacytoid dendritic cell neoplasm can present as an isolated purplish nodule or bruiselike papule or more commonly as disseminated purplish nodules, papules, and macules. Isolated nodules are found on the head and lower limbs and can be more than 10 cm in diameter. Peripheral blood and bone marrow may be minimally involved at presentation but invariably become involved with the progression of disease. Cytopenia can occur at diagnosis and in a minority of severe cases indicates bone marrow failure.^2-6

Skin involvement of BPDCN is thought to be secondary to the expression of skin migration molecules, such as cutaneous lymphocyte-associated antigen, one of the E-selectin ligands, which binds to E-selectin on high endothelial venules. In addition, the local dermal microenvironment of chemokines binding CXCR3, CXCR4, CCR6, or CCR7 present on neoplastic cells possibly leads to skin involvement. The full mechanism underlying the cutaneous tropism is still to be elucidated.^4-7 Infiltration of the oral mucosa is seen in some patients, but it may be underreported. Mucosal disease typically appears similarly to cutaneous disease.

The cutaneous differential diagnosis for BPDCN depends on the clinical presentation, extent of disease spread, and thickness of infiltration. It includes common nonneoplastic diseases such as traumatic ecchymoses; purpuric disorders; extramedullary hematopoiesis; and soft-tissue neoplasms such as angiosarcoma, Kaposi sarcoma, neuroblastoma, and vascular metastases, as well as skin involvement by other hematologic neoplasms. An adequate incisional biopsy rather than a punch or shave biopsy is recommended for diagnosis. Dermatologists should alert the pathologist that BPDCN is in the clinical differential diagnosis when possible so that judicious use of appropriate immunophenotypic markers such as CD123, CD4, CD56, and T-cell leukemia/lymphoma protein 1 will avoid misdiagnosis of this aggressive condition, in addition to excluding acute myeloid leukemia, which also may express 3 of the above markers. However, most cases of acute myeloid leukemia lack terminal deoxynucleotidyl transferase (TdT) and express monocytic and other myeloid markers. Terminal deoxynucleotidyl transferase is positive in approximately one-third of cases of BPDCN, with expression in 10% to 80% of cells.¹

It is important to include BPDCN in the differential diagnosis of immunophenotypically aberrant hematologic tumors. Diffuse large B-cell lymphoma, leg type, accounts for 4% of all primary cutaneous B-cell lymphomas.¹ Compared with BPDCN, diffuse large B-cell lymphoma usually occurs in an older age group and is of B-cell lineage. Morphologically, these neoplasms are composed of a monotonous, diffuse, nonepidermotropic infiltrate of confluent sheets of centroblasts and immunoblasts (Figure 1). They may share immunohistochemical markers of CD79a, multiple myeloma 1, Bcl-2, and Bcl-6; however, they lack plasmacytoid dendritic cell (PDC)– associated antigens such as CD4, CD56, CD123, and T-cell leukemia/lymphoma protein 1.¹

Adult T-cell leukemia/lymphoma is a neoplasm histologically composed of highly pleomorphic medium- to large-sized T cells with an irregular multilobated nuclear contour, so-called flower cells, in the peripheral blood. The nuclear chromatin is coarse and clumped with prominent nucleoli. Blastlike cells with dispersed chromatin are present in variable proportions. Most patients present with widespread lymph node and peripheral blood involvement. Skin is involved in more than half of patients with an epidermal as well as dermal pattern of infiltration (mainly perivascular)(Figure 2). Adult T-cell leukemia/lymphoma is endemic in several regions of the world, and the distribution is closely linked to the prevalence of human T-cell lymphotropic virus type 1 in the population. This neoplasm is of T-cell lineage and may share CD4 but not PDC-associated antigens with BPDCN.¹

Cutaneous involvement by T-cell lymphoblastic leukemia/lymphoma (T-LBL) is a rare occurrence with a frequency of approximately 4.3%.8 T-cell lymphoblastic leukemia/lymphoma usually presents as multiple skin lesions throughout the body. Almost all cutaneous T-LBL cases are seen in association with bone marrow and/or mediastinal, lymph node, or extranodal involvement. Cutaneous T-LBLs present as a diffuse monomorphous infiltrate located in the entire dermis and subcutis without epidermotropism, composed of medium to large blasts with finely dispersed chromatin and relatively prominent nucleoli (Figure 3). Immunophenotyping studies show an immature T-cell immunophenotype, with expression of TdT (usually uniform), CD7, and cytoplasmic CD3 and an absence of PDC-associated antigens.⁸

Primary cutaneous γδ T-cell lymphoma (PCGDTL) is a neoplasm primarily involving the skin. Often rapidly fatal, PCGDTL has a broad clinical spectrum that may include indolent variants—subcutaneous, epidermotropic, and dermal. Patients typically present with nodular lesions that progress to ulceration and necrosis. Early lesions can be confused with erythema nodosum, mycosis fungoides, or infection. Histologically, they show variable epidermotropism as well as dermal and subcutaneous involvement by medium to large cells with coarse clumped chromatin (Figure 4). Large blastic cells with vesicular nuclei and prominent nucleoli are infrequent. In contrast to BPCDN, the neoplastic lymphocytes in dermal and subcutaneous PCGDTL typically are positive for T-cell intracellular antigen-1 and granzyme B with loss of CD4.⁹

At the time of presentation, 27% to 87% of BPDCN patients will have bone marrow involvement, 22% to 28% will have blood involvement, and 6% to 41% will have lymph node involvement.^{1-4,6,7,10,11} The clinical course is aggressive, with a median survival of 10.0 to 19.8 months, irrespective of the initial pattern of disease.¹ Most cases have shown initial response to multiagent chemotherapy, but relapses with subsequent resistance to drugs regularly have been observed. Age has an adverse impact of prognosis. Low TdT expression has been associated with shorter survival.¹ Approximately 10% to 20% of cases of BPDCN are associated with or develop into chronic myelogenous leukemia, myelodysplastic syndrome, or acute myeloid leukemia.^1,4 Pediatric patients have a greater 5-year overall survival rate than older patients, and overall survival worsens with increasing age. The extent of cutaneous involvement and presence of systemic involvement at initial presentation do not seem to be strong predictors of survival.^{1,2,5-7,10-12} In a retrospective analysis of 90 patients, Julia et al¹² found that the type of skin disease did not predict survival. Specifically, the presence of nodular lesions and disseminated skin involvement were not adverse prognostic factors compared with macular lesions limited to 1 or 2 body areas.¹²

The Diagnosis: Blastic Plasmacytoid Dendritic Cell Neoplasm

A diagnosis of blastic plasmacytoid dendritic cell neoplasm (BPDCN) was rendered. Subsequent needle core biopsy of a left axillary lymph node as well as bone marrow aspiration and biopsy revealed a similar diffuse blastoid infiltrate with an identical immunophenotype to that in the skin biopsy from the pretibial mass and peripheral blood.

Previously known as blastic natural killer cell leukemia/lymphoma or agranular CD4+/CD56+ hematodermic neoplasm/tumor, BPDCN is a rare, clinically aggressive hematologic malignancy derived from the precursors of plasmacytoid dendritic cells. It often is diagnostically challenging, particularly when presenting at noncutaneous sites and in unusual (young) patient populations.¹ It was included with other myeloid neoplasms in the 2008 World Health Organization classification; however, in the 2017 classification it was categorized as a separate entity. Blastic plasmacytoid dendritic cell neoplasm typically presents in the skin of elderly patients (age range at diagnosis, 61–67 years) with or without bone marrow involvement and systemic dissemination.^1,2 The skin is the most common clinical site of disease in typical cases of BPDCN and often precedes bone marrow involvement. Thus, skin biopsy often is the key to making the diagnosis. Diagnosis of BPDCN may be delayed because of diagnostic pitfalls. Patients usually present with asymptomatic solitary or multiple lesions.^3-5 Blastic plasmacytoid dendritic cell neoplasm can present as an isolated purplish nodule or bruiselike papule or more commonly as disseminated purplish nodules, papules, and macules. Isolated nodules are found on the head and lower limbs and can be more than 10 cm in diameter. Peripheral blood and bone marrow may be minimally involved at presentation but invariably become involved with the progression of disease. Cytopenia can occur at diagnosis and in a minority of severe cases indicates bone marrow failure.^2-6

Skin involvement of BPDCN is thought to be secondary to the expression of skin migration molecules, such as cutaneous lymphocyte-associated antigen, one of the E-selectin ligands, which binds to E-selectin on high endothelial venules. In addition, the local dermal microenvironment of chemokines binding CXCR3, CXCR4, CCR6, or CCR7 present on neoplastic cells possibly leads to skin involvement. The full mechanism underlying the cutaneous tropism is still to be elucidated.^4-7 Infiltration of the oral mucosa is seen in some patients, but it may be underreported. Mucosal disease typically appears similarly to cutaneous disease.

The cutaneous differential diagnosis for BPDCN depends on the clinical presentation, extent of disease spread, and thickness of infiltration. It includes common nonneoplastic diseases such as traumatic ecchymoses; purpuric disorders; extramedullary hematopoiesis; and soft-tissue neoplasms such as angiosarcoma, Kaposi sarcoma, neuroblastoma, and vascular metastases, as well as skin involvement by other hematologic neoplasms. An adequate incisional biopsy rather than a punch or shave biopsy is recommended for diagnosis. Dermatologists should alert the pathologist that BPDCN is in the clinical differential diagnosis when possible so that judicious use of appropriate immunophenotypic markers such as CD123, CD4, CD56, and T-cell leukemia/lymphoma protein 1 will avoid misdiagnosis of this aggressive condition, in addition to excluding acute myeloid leukemia, which also may express 3 of the above markers. However, most cases of acute myeloid leukemia lack terminal deoxynucleotidyl transferase (TdT) and express monocytic and other myeloid markers. Terminal deoxynucleotidyl transferase is positive in approximately one-third of cases of BPDCN, with expression in 10% to 80% of cells.¹

It is important to include BPDCN in the differential diagnosis of immunophenotypically aberrant hematologic tumors. Diffuse large B-cell lymphoma, leg type, accounts for 4% of all primary cutaneous B-cell lymphomas.¹ Compared with BPDCN, diffuse large B-cell lymphoma usually occurs in an older age group and is of B-cell lineage. Morphologically, these neoplasms are composed of a monotonous, diffuse, nonepidermotropic infiltrate of confluent sheets of centroblasts and immunoblasts (Figure 1). They may share immunohistochemical markers of CD79a, multiple myeloma 1, Bcl-2, and Bcl-6; however, they lack plasmacytoid dendritic cell (PDC)– associated antigens such as CD4, CD56, CD123, and T-cell leukemia/lymphoma protein 1.¹

Adult T-cell leukemia/lymphoma is a neoplasm histologically composed of highly pleomorphic medium- to large-sized T cells with an irregular multilobated nuclear contour, so-called flower cells, in the peripheral blood. The nuclear chromatin is coarse and clumped with prominent nucleoli. Blastlike cells with dispersed chromatin are present in variable proportions. Most patients present with widespread lymph node and peripheral blood involvement. Skin is involved in more than half of patients with an epidermal as well as dermal pattern of infiltration (mainly perivascular)(Figure 2). Adult T-cell leukemia/lymphoma is endemic in several regions of the world, and the distribution is closely linked to the prevalence of human T-cell lymphotropic virus type 1 in the population. This neoplasm is of T-cell lineage and may share CD4 but not PDC-associated antigens with BPDCN.¹

Cutaneous involvement by T-cell lymphoblastic leukemia/lymphoma (T-LBL) is a rare occurrence with a frequency of approximately 4.3%.8 T-cell lymphoblastic leukemia/lymphoma usually presents as multiple skin lesions throughout the body. Almost all cutaneous T-LBL cases are seen in association with bone marrow and/or mediastinal, lymph node, or extranodal involvement. Cutaneous T-LBLs present as a diffuse monomorphous infiltrate located in the entire dermis and subcutis without epidermotropism, composed of medium to large blasts with finely dispersed chromatin and relatively prominent nucleoli (Figure 3). Immunophenotyping studies show an immature T-cell immunophenotype, with expression of TdT (usually uniform), CD7, and cytoplasmic CD3 and an absence of PDC-associated antigens.⁸

Primary cutaneous γδ T-cell lymphoma (PCGDTL) is a neoplasm primarily involving the skin. Often rapidly fatal, PCGDTL has a broad clinical spectrum that may include indolent variants—subcutaneous, epidermotropic, and dermal. Patients typically present with nodular lesions that progress to ulceration and necrosis. Early lesions can be confused with erythema nodosum, mycosis fungoides, or infection. Histologically, they show variable epidermotropism as well as dermal and subcutaneous involvement by medium to large cells with coarse clumped chromatin (Figure 4). Large blastic cells with vesicular nuclei and prominent nucleoli are infrequent. In contrast to BPCDN, the neoplastic lymphocytes in dermal and subcutaneous PCGDTL typically are positive for T-cell intracellular antigen-1 and granzyme B with loss of CD4.⁹

At the time of presentation, 27% to 87% of BPDCN patients will have bone marrow involvement, 22% to 28% will have blood involvement, and 6% to 41% will have lymph node involvement.^{1-4,6,7,10,11} The clinical course is aggressive, with a median survival of 10.0 to 19.8 months, irrespective of the initial pattern of disease.¹ Most cases have shown initial response to multiagent chemotherapy, but relapses with subsequent resistance to drugs regularly have been observed. Age has an adverse impact of prognosis. Low TdT expression has been associated with shorter survival.¹ Approximately 10% to 20% of cases of BPDCN are associated with or develop into chronic myelogenous leukemia, myelodysplastic syndrome, or acute myeloid leukemia.^1,4 Pediatric patients have a greater 5-year overall survival rate than older patients, and overall survival worsens with increasing age. The extent of cutaneous involvement and presence of systemic involvement at initial presentation do not seem to be strong predictors of survival.^{1,2,5-7,10-12} In a retrospective analysis of 90 patients, Julia et al¹² found that the type of skin disease did not predict survival. Specifically, the presence of nodular lesions and disseminated skin involvement were not adverse prognostic factors compared with macular lesions limited to 1 or 2 body areas.¹²

Researchers have identified markers in saliva that are differentially expressed in children with autism spectrum disorder (ASD) who have gastrointestinal (GI) disturbances.

These findings mark the beginning of an understanding of the biological differences separating kids with ASD with and without GI disturbances, study investigator David Q. Beversdorf, MD, professor of radiology, neurology and psychology, department of psychological sciences, University of Missouri, Columbia, told this news organization.

“The hope is this will lead us in future to markers that help guide targeted precision treatments of gastrointestinal disorders” in children with autism, with the ultimate goal of improving their quality of life, said Dr. Beversdorf.

The study was published online Jan. 20 in Frontiers in Psychiatry.
 

Anxiety a key driver?

GI disorders, particularly constipation, are common in children with ASD. Previous research by Dr. Beversdorf and colleagues suggests that anxiety may be driving the relationship between gut disturbances and autism.

Research shows some children with ASD respond well to traditional treatments such as laxatives, while others do not. However, the reasons for this are unclear.

“It would be great to know who those great responders are,” said Dr. Beversdorf. “Subtyping and using biomarkers might be biologically meaningful” because this could identify distinct groups.

The case-control study included 898 children aged 18-73 months recruited from outpatient pediatric clinics affiliated with seven academic medical centers across the United States. The average age of the sample was 44 months and participants were mainly White (76%), non-Hispanic (89%), and male (73%).

The children fell into three neurodevelopmental categories: ASD (n = 503), non-ASD developmental delay (DD, n = 205), and typical development (TD, n = 190).

ASD was diagnosed using standardized assessment tools including the Autism Diagnostic Observation Scale, second edition (ADOS-2). DD participants had delays in gross motor skills, fine motor skills, language, or cognitive development but did not meet criteria for ASD.

Including children with DD could address whether biological markers are specific to autism or to developmental disorders in general, noted Dr. Beversdorf.

TD participants, recruited at the time of their annual well-child visit, did not exhibit developmental delays.
 

Links to GI disturbance, behavior

Researchers subdivided participants into those with GI disturbances (n = 184) and those without these disturbances (n = 714). This was based on medical record review and parental report of disorders such as constipation, reflux, chronic diarrhea or abdominal pain, and food intolerance.

As expected, investigators found more children with ASD reported GI disturbance (22%) than with TD (10%). In children with ASD, rates of constipation (11%) and reflux (6%) were higher than rates among those with TD (3% and 0.5%, respectively).

However, rates of GI disturbances in children with ASD were similar to those with DD.

Investigators used a swab to obtain a saliva sample from participants in a nonfasting state. Saliva is a feasible and often favored source for sampling GI-related biology. Unlike stool microbiome, the saliva microbiome can be repeatedly sampled on demand and has shown resilience to antibiotics.

Researchers examined numerous RNAs, which are “incredibly biologically relevant,” said Dr. Beversdorf.

Investigators compared levels of 1,821 micro-transcriptome features across neurodevelopmental status and the presence or absence of GI disorders.

They also examined micro-transcriptome levels among GI subgroups (constipation, reflux, food intolerance, other GI condition, no GI condition). In addition, they identified RNAs that differed among children taking three common GI medications. These included probiotics, reflux medication, or laxatives.

The investigators found five piwi-interacting RNAs, which are small noncoding RNA molecules and three microbial RNAs in saliva that displayed an interaction between developmental status and GI disturbance. Fifty-seven salivary RNAs differed between GI subgroups, with microRNA differences found between food intolerance and reflux groups being the most common.

The analysis identified 12 microRNAs that displayed relationships with GI disturbance, behavior, and GI medication use.
 

First exploration

However, Dr. Beversdorf cautioned about the medication finding. “I can’t speak confidently about what we see there because with each group you get much, much smaller sample sizes with each individual treatment approach.”

The researchers looked at downstream targets of the 12 microRNAs and found involvement with 13 physiologic pathways. These included long-term depression, metabolism, and digestion pathways.

The metabolism and digestion pathways make sense, but it’s unclear why an addiction-related pathway would be involved, said Dr. Beversdorf. However, he noted children with autism do display obsessive features.

Experts don’t know if RNA changes are a cause of, or a response to, GI problems. “It could be the pain of constipation is triggering, say, these addiction pathway changes,” said Dr. Beversdorf.

The study is the “first exploration” into possible specific targets for treating GI disturbances in autism, said Dr. Beversdorf. “We hope these biomarkers will eventually give us an indication of which patients are going to respond to the individual approach to treating their constipation, their diarrhea, or whatever it is.”

The investigators plan to study whether RNA biomarkers determine which patients respond to different treatments targeting constipation, said Dr. Beversdorf.

A study limitation was that GI disturbances were not assessed by physicians. In addition, the term “GI disturbance” groups together loosely related pathology occurring in the GI tract, although there are important physiologic differences between conditions such as constipation and reflux.

The study received funding from the National Institutes of Health.

A version of this article first appeared on Medscape.com.

Researchers have identified markers in saliva that are differentially expressed in children with autism spectrum disorder (ASD) who have gastrointestinal (GI) disturbances.

These findings mark the beginning of an understanding of the biological differences separating kids with ASD with and without GI disturbances, study investigator David Q. Beversdorf, MD, professor of radiology, neurology and psychology, department of psychological sciences, University of Missouri, Columbia, told this news organization.

“The hope is this will lead us in future to markers that help guide targeted precision treatments of gastrointestinal disorders” in children with autism, with the ultimate goal of improving their quality of life, said Dr. Beversdorf.

The study was published online Jan. 20 in Frontiers in Psychiatry.
 

Anxiety a key driver?

GI disorders, particularly constipation, are common in children with ASD. Previous research by Dr. Beversdorf and colleagues suggests that anxiety may be driving the relationship between gut disturbances and autism.

Research shows some children with ASD respond well to traditional treatments such as laxatives, while others do not. However, the reasons for this are unclear.

“It would be great to know who those great responders are,” said Dr. Beversdorf. “Subtyping and using biomarkers might be biologically meaningful” because this could identify distinct groups.

The case-control study included 898 children aged 18-73 months recruited from outpatient pediatric clinics affiliated with seven academic medical centers across the United States. The average age of the sample was 44 months and participants were mainly White (76%), non-Hispanic (89%), and male (73%).

The children fell into three neurodevelopmental categories: ASD (n = 503), non-ASD developmental delay (DD, n = 205), and typical development (TD, n = 190).

ASD was diagnosed using standardized assessment tools including the Autism Diagnostic Observation Scale, second edition (ADOS-2). DD participants had delays in gross motor skills, fine motor skills, language, or cognitive development but did not meet criteria for ASD.

Including children with DD could address whether biological markers are specific to autism or to developmental disorders in general, noted Dr. Beversdorf.

TD participants, recruited at the time of their annual well-child visit, did not exhibit developmental delays.
 

Links to GI disturbance, behavior

Researchers subdivided participants into those with GI disturbances (n = 184) and those without these disturbances (n = 714). This was based on medical record review and parental report of disorders such as constipation, reflux, chronic diarrhea or abdominal pain, and food intolerance.

As expected, investigators found more children with ASD reported GI disturbance (22%) than with TD (10%). In children with ASD, rates of constipation (11%) and reflux (6%) were higher than rates among those with TD (3% and 0.5%, respectively).

However, rates of GI disturbances in children with ASD were similar to those with DD.

Investigators used a swab to obtain a saliva sample from participants in a nonfasting state. Saliva is a feasible and often favored source for sampling GI-related biology. Unlike stool microbiome, the saliva microbiome can be repeatedly sampled on demand and has shown resilience to antibiotics.

Researchers examined numerous RNAs, which are “incredibly biologically relevant,” said Dr. Beversdorf.

Investigators compared levels of 1,821 micro-transcriptome features across neurodevelopmental status and the presence or absence of GI disorders.

They also examined micro-transcriptome levels among GI subgroups (constipation, reflux, food intolerance, other GI condition, no GI condition). In addition, they identified RNAs that differed among children taking three common GI medications. These included probiotics, reflux medication, or laxatives.

The investigators found five piwi-interacting RNAs, which are small noncoding RNA molecules and three microbial RNAs in saliva that displayed an interaction between developmental status and GI disturbance. Fifty-seven salivary RNAs differed between GI subgroups, with microRNA differences found between food intolerance and reflux groups being the most common.

The analysis identified 12 microRNAs that displayed relationships with GI disturbance, behavior, and GI medication use.
 

First exploration

However, Dr. Beversdorf cautioned about the medication finding. “I can’t speak confidently about what we see there because with each group you get much, much smaller sample sizes with each individual treatment approach.”

The researchers looked at downstream targets of the 12 microRNAs and found involvement with 13 physiologic pathways. These included long-term depression, metabolism, and digestion pathways.

The metabolism and digestion pathways make sense, but it’s unclear why an addiction-related pathway would be involved, said Dr. Beversdorf. However, he noted children with autism do display obsessive features.

Experts don’t know if RNA changes are a cause of, or a response to, GI problems. “It could be the pain of constipation is triggering, say, these addiction pathway changes,” said Dr. Beversdorf.

The study is the “first exploration” into possible specific targets for treating GI disturbances in autism, said Dr. Beversdorf. “We hope these biomarkers will eventually give us an indication of which patients are going to respond to the individual approach to treating their constipation, their diarrhea, or whatever it is.”

The investigators plan to study whether RNA biomarkers determine which patients respond to different treatments targeting constipation, said Dr. Beversdorf.

A study limitation was that GI disturbances were not assessed by physicians. In addition, the term “GI disturbance” groups together loosely related pathology occurring in the GI tract, although there are important physiologic differences between conditions such as constipation and reflux.

The study received funding from the National Institutes of Health.

A version of this article first appeared on Medscape.com.

Researchers have identified markers in saliva that are differentially expressed in children with autism spectrum disorder (ASD) who have gastrointestinal (GI) disturbances.

These findings mark the beginning of an understanding of the biological differences separating kids with ASD with and without GI disturbances, study investigator David Q. Beversdorf, MD, professor of radiology, neurology and psychology, department of psychological sciences, University of Missouri, Columbia, told this news organization.

“The hope is this will lead us in future to markers that help guide targeted precision treatments of gastrointestinal disorders” in children with autism, with the ultimate goal of improving their quality of life, said Dr. Beversdorf.

The study was published online Jan. 20 in Frontiers in Psychiatry.
 

Anxiety a key driver?

GI disorders, particularly constipation, are common in children with ASD. Previous research by Dr. Beversdorf and colleagues suggests that anxiety may be driving the relationship between gut disturbances and autism.

Research shows some children with ASD respond well to traditional treatments such as laxatives, while others do not. However, the reasons for this are unclear.

“It would be great to know who those great responders are,” said Dr. Beversdorf. “Subtyping and using biomarkers might be biologically meaningful” because this could identify distinct groups.

The case-control study included 898 children aged 18-73 months recruited from outpatient pediatric clinics affiliated with seven academic medical centers across the United States. The average age of the sample was 44 months and participants were mainly White (76%), non-Hispanic (89%), and male (73%).

The children fell into three neurodevelopmental categories: ASD (n = 503), non-ASD developmental delay (DD, n = 205), and typical development (TD, n = 190).

ASD was diagnosed using standardized assessment tools including the Autism Diagnostic Observation Scale, second edition (ADOS-2). DD participants had delays in gross motor skills, fine motor skills, language, or cognitive development but did not meet criteria for ASD.

Including children with DD could address whether biological markers are specific to autism or to developmental disorders in general, noted Dr. Beversdorf.

TD participants, recruited at the time of their annual well-child visit, did not exhibit developmental delays.
 

Links to GI disturbance, behavior

Researchers subdivided participants into those with GI disturbances (n = 184) and those without these disturbances (n = 714). This was based on medical record review and parental report of disorders such as constipation, reflux, chronic diarrhea or abdominal pain, and food intolerance.

As expected, investigators found more children with ASD reported GI disturbance (22%) than with TD (10%). In children with ASD, rates of constipation (11%) and reflux (6%) were higher than rates among those with TD (3% and 0.5%, respectively).

However, rates of GI disturbances in children with ASD were similar to those with DD.

Investigators used a swab to obtain a saliva sample from participants in a nonfasting state. Saliva is a feasible and often favored source for sampling GI-related biology. Unlike stool microbiome, the saliva microbiome can be repeatedly sampled on demand and has shown resilience to antibiotics.

Researchers examined numerous RNAs, which are “incredibly biologically relevant,” said Dr. Beversdorf.

Investigators compared levels of 1,821 micro-transcriptome features across neurodevelopmental status and the presence or absence of GI disorders.

They also examined micro-transcriptome levels among GI subgroups (constipation, reflux, food intolerance, other GI condition, no GI condition). In addition, they identified RNAs that differed among children taking three common GI medications. These included probiotics, reflux medication, or laxatives.

The investigators found five piwi-interacting RNAs, which are small noncoding RNA molecules and three microbial RNAs in saliva that displayed an interaction between developmental status and GI disturbance. Fifty-seven salivary RNAs differed between GI subgroups, with microRNA differences found between food intolerance and reflux groups being the most common.

The analysis identified 12 microRNAs that displayed relationships with GI disturbance, behavior, and GI medication use.
 

First exploration

However, Dr. Beversdorf cautioned about the medication finding. “I can’t speak confidently about what we see there because with each group you get much, much smaller sample sizes with each individual treatment approach.”

The researchers looked at downstream targets of the 12 microRNAs and found involvement with 13 physiologic pathways. These included long-term depression, metabolism, and digestion pathways.

The metabolism and digestion pathways make sense, but it’s unclear why an addiction-related pathway would be involved, said Dr. Beversdorf. However, he noted children with autism do display obsessive features.

Experts don’t know if RNA changes are a cause of, or a response to, GI problems. “It could be the pain of constipation is triggering, say, these addiction pathway changes,” said Dr. Beversdorf.

The study is the “first exploration” into possible specific targets for treating GI disturbances in autism, said Dr. Beversdorf. “We hope these biomarkers will eventually give us an indication of which patients are going to respond to the individual approach to treating their constipation, their diarrhea, or whatever it is.”

The investigators plan to study whether RNA biomarkers determine which patients respond to different treatments targeting constipation, said Dr. Beversdorf.

A study limitation was that GI disturbances were not assessed by physicians. In addition, the term “GI disturbance” groups together loosely related pathology occurring in the GI tract, although there are important physiologic differences between conditions such as constipation and reflux.

The study received funding from the National Institutes of Health.

A version of this article first appeared on Medscape.com.

Testing is ongoing after more than 4,600 veterans who had received care at the Carl Vinson Veterans Affairs Medical Center in Dublin, Georgia, were alerted that they may have been exposed to HIV, hepatitis B, and hepatitis C. The exposure was due to improperly sterilized equipment. At least some of the patients have tested positive, but the facility has not indicated the number, the diseases, or whether the infections were the result of the exposure.

A mid-January internal review at the hospital found that not all steps were being followed in the procedures for sterilizing equipment between patients. Patients who had dentistry, endoscopy, urology, podiatry, optometry, or surgical procedures in 2021 may have been exposed to blood-borne pathogens.

In response, the VA sent teams from other hospitals to help, including a team from the Augusta Veterans Affairs Medical Center to reprocess all equipment and staff from VA facilities in Atlanta, South Carolina, and Alabama to provide personnel training. All staff at Carl Vinson Veterans Affairs Medical Center have since been retrained on all current guidelines.

The hospital says it’s still testing exposed veterans. Hospital spokesperson James Huckfeldt told a Macon-based newspaper, The Telegraph, that veterans with positive test results will undergo additional testing to determine whether the transmission is new or preexisting. “The findings from the additional testing will be used to accurately diagnose any impacted veterans and ensure that they receive appropriate medical treatment,” he said.

Manuel M. Davila, director of the hospital, sent letters to the patients at risk, alerting them to the exposure. “We sincerely apologize and accept responsibility for this mistake and are taking steps to prevent it from happening in the future,” Davilla wrote. “This event is unacceptable to us as well, and we want to work with you to correct the situation and ensure your safety and well-being. Because your safety is important to us and because we want to honor your trust in us, we want you to know that when concerns are raised over our processes or procedures, we take immediate steps to stop everything and make sure things are.”

Davilla reassured the veterans that “we are confident that the risk of infectious disease is very low.”

The Carl Vinson Medical Center has set up a communication center to answer questions for veterans: (478) 274-5400.

Testing is ongoing after more than 4,600 veterans who had received care at the Carl Vinson Veterans Affairs Medical Center in Dublin, Georgia, were alerted that they may have been exposed to HIV, hepatitis B, and hepatitis C. The exposure was due to improperly sterilized equipment. At least some of the patients have tested positive, but the facility has not indicated the number, the diseases, or whether the infections were the result of the exposure.

A mid-January internal review at the hospital found that not all steps were being followed in the procedures for sterilizing equipment between patients. Patients who had dentistry, endoscopy, urology, podiatry, optometry, or surgical procedures in 2021 may have been exposed to blood-borne pathogens.

In response, the VA sent teams from other hospitals to help, including a team from the Augusta Veterans Affairs Medical Center to reprocess all equipment and staff from VA facilities in Atlanta, South Carolina, and Alabama to provide personnel training. All staff at Carl Vinson Veterans Affairs Medical Center have since been retrained on all current guidelines.

The hospital says it’s still testing exposed veterans. Hospital spokesperson James Huckfeldt told a Macon-based newspaper, The Telegraph, that veterans with positive test results will undergo additional testing to determine whether the transmission is new or preexisting. “The findings from the additional testing will be used to accurately diagnose any impacted veterans and ensure that they receive appropriate medical treatment,” he said.

Manuel M. Davila, director of the hospital, sent letters to the patients at risk, alerting them to the exposure. “We sincerely apologize and accept responsibility for this mistake and are taking steps to prevent it from happening in the future,” Davilla wrote. “This event is unacceptable to us as well, and we want to work with you to correct the situation and ensure your safety and well-being. Because your safety is important to us and because we want to honor your trust in us, we want you to know that when concerns are raised over our processes or procedures, we take immediate steps to stop everything and make sure things are.”

Davilla reassured the veterans that “we are confident that the risk of infectious disease is very low.”

The Carl Vinson Medical Center has set up a communication center to answer questions for veterans: (478) 274-5400.

Testing is ongoing after more than 4,600 veterans who had received care at the Carl Vinson Veterans Affairs Medical Center in Dublin, Georgia, were alerted that they may have been exposed to HIV, hepatitis B, and hepatitis C. The exposure was due to improperly sterilized equipment. At least some of the patients have tested positive, but the facility has not indicated the number, the diseases, or whether the infections were the result of the exposure.

A mid-January internal review at the hospital found that not all steps were being followed in the procedures for sterilizing equipment between patients. Patients who had dentistry, endoscopy, urology, podiatry, optometry, or surgical procedures in 2021 may have been exposed to blood-borne pathogens.

In response, the VA sent teams from other hospitals to help, including a team from the Augusta Veterans Affairs Medical Center to reprocess all equipment and staff from VA facilities in Atlanta, South Carolina, and Alabama to provide personnel training. All staff at Carl Vinson Veterans Affairs Medical Center have since been retrained on all current guidelines.

The hospital says it’s still testing exposed veterans. Hospital spokesperson James Huckfeldt told a Macon-based newspaper, The Telegraph, that veterans with positive test results will undergo additional testing to determine whether the transmission is new or preexisting. “The findings from the additional testing will be used to accurately diagnose any impacted veterans and ensure that they receive appropriate medical treatment,” he said.

Manuel M. Davila, director of the hospital, sent letters to the patients at risk, alerting them to the exposure. “We sincerely apologize and accept responsibility for this mistake and are taking steps to prevent it from happening in the future,” Davilla wrote. “This event is unacceptable to us as well, and we want to work with you to correct the situation and ensure your safety and well-being. Because your safety is important to us and because we want to honor your trust in us, we want you to know that when concerns are raised over our processes or procedures, we take immediate steps to stop everything and make sure things are.”

Davilla reassured the veterans that “we are confident that the risk of infectious disease is very low.”

The Carl Vinson Medical Center has set up a communication center to answer questions for veterans: (478) 274-5400.

Compared with control treatment among critically ill adults, low-molecular-weight heparin (LMWH) reduces the incidence of deep vein thrombosis (DVT), according to a systematic review and network meta-analysis of randomized clinical trials (RCTs) published in CHEST. The analysis showed also that risk of DVT may be reduced by unfractionated heparin (UFH) and by mechanical compressive devices, although LMWH should be considered the primary pharmacologic agent for thromboprophylaxis.

Risk of venous thromboembolism (VTE), including DVT and pulmonary embolism (PE), is heightened in critically ill patients. VTE incidence is highest in major surgery and trauma patients, and mortality estimates from PE among intensive care unit patients are as high as 12%. Clinical practice guidelines recommend prophylaxis with pharmacologic agents over no prophylaxis in critically ill adults. Shannon M. Fernando, MD, of the University of Ottawa and colleagues examined the comparative efficacy and safety of various agents for VTE prophylaxis in critically ill patients through a review of 13 RCTs (9,619 patients) in six databases (Medline, PubMed, EMBASE, Scopus, Webof Science, and the Cochrane Database of Systematic Reviews). The ICU patients received a variety of therapies including pharmacologic, mechanical, or their combination for thromboprophylaxis. The control population consisted of a composite of no prophylaxis, placebo, or compression stockings only.
 

Indicative results

Analysis showed LMWH to reduce the incidence of DVT (odds ratio, 0.59; high certainty), while UFH may reduce the incidence of DVT (OR, 0.82; low certainty). Compared with UFH, LMWH probably reduces DVT (OR, 0.72; moderate certainty). Compressive devices, based on low-certainty evidence, may reduce risk of DVT, compared with control treatments (OR, 0.85).

The effect of combination therapy on DVT, compared with either therapy alone was unclear (very low certainty). The large-scale (2,000 patients) PREVENT trial in 2019, Dr. Fernando noted in an interview, found that adding compression therapy to pharmacologic therapy produced no reduction in proximal lower limb DVT.

“Ultimately, I think that, even if multiple RCTs and subsequent meta-analyses were performed, at best we would find that the incremental benefit of combination therapy is very minimal,” Dr. Fernando stated.

The findings provide evidence supporting LMWH and UFH use as compared with no pharmacologic prophylaxis for prevention of DVT, according to the researchers. While a similar certainty of effect in reducing PE was not found, evidence with moderate certainty suggested that LMWH and UFH probably reduce the incidence of any VTE, compared with no pharmacologic prophylaxis. Cost-effectiveness modeling that takes into account VTE incidence supports the practice. “If you’re reducing the incidence of DVT, it’s likely you’re similarly reducing incidence of PE, though I will agree that currently the data do not support this,” he said in an interview.

Noting that, while support in existing literature for any specific agent is controversial, the authors cite that American Society of Hematology guidelines suggest considering LMWH over UFH in critically ill patients, and that their findings lend support to that position. Regarding safety, pair-wise meta-analysis did not reveal clear major bleeding incidence differences between UFH and LMWH.
 

In and out of the ICU

Concordant with studies outside the ICU finding that heparin-induced thrombocytopenia (HIT) incidence is lower among patients receiving LMWH rather than UFH for VTE prophylaxis, the meta-analysis revealed a lower incidence of HIT among the critically ill receiving LMWH, but with evidence that was of low certainty.

Uncertainty around the optimal approach to VTE prophylaxis in the ICU along with wide variations in clinical practice persist despite recognition of the issue’s importance, note Major Michael J. McMahon, MD, of Honolulu and Colonel Aaron B. Holley, MD, of Bethesda, Md., authors of an accompanying editorial, “To generalize or not to generalize? The approach to VTE prophylaxis”. They acknowledge also that the Fernando et al. analysis yields important insights into VTE prevention in the ICU. Rhetorically raising the question, “Can we now say without doubt that LMWH is the preferred agent for all patients in the ICU?” – they responded, “probably.” Not entirely eliminated, they observe, is the possibility that a specific patient subgroup may benefit from one agent compared with another. They add, “We came away more confident that LMWH should be the default choice for VTE prevention in the ICU.”

Dr. Fernando and coauthors listed multiple disclosures, but declared that they received no financial support. Dr. McMahon and Dr. Holley declared that they have no disclosures.

Compared with control treatment among critically ill adults, low-molecular-weight heparin (LMWH) reduces the incidence of deep vein thrombosis (DVT), according to a systematic review and network meta-analysis of randomized clinical trials (RCTs) published in CHEST. The analysis showed also that risk of DVT may be reduced by unfractionated heparin (UFH) and by mechanical compressive devices, although LMWH should be considered the primary pharmacologic agent for thromboprophylaxis.

Risk of venous thromboembolism (VTE), including DVT and pulmonary embolism (PE), is heightened in critically ill patients. VTE incidence is highest in major surgery and trauma patients, and mortality estimates from PE among intensive care unit patients are as high as 12%. Clinical practice guidelines recommend prophylaxis with pharmacologic agents over no prophylaxis in critically ill adults. Shannon M. Fernando, MD, of the University of Ottawa and colleagues examined the comparative efficacy and safety of various agents for VTE prophylaxis in critically ill patients through a review of 13 RCTs (9,619 patients) in six databases (Medline, PubMed, EMBASE, Scopus, Webof Science, and the Cochrane Database of Systematic Reviews). The ICU patients received a variety of therapies including pharmacologic, mechanical, or their combination for thromboprophylaxis. The control population consisted of a composite of no prophylaxis, placebo, or compression stockings only.
 

Indicative results

Analysis showed LMWH to reduce the incidence of DVT (odds ratio, 0.59; high certainty), while UFH may reduce the incidence of DVT (OR, 0.82; low certainty). Compared with UFH, LMWH probably reduces DVT (OR, 0.72; moderate certainty). Compressive devices, based on low-certainty evidence, may reduce risk of DVT, compared with control treatments (OR, 0.85).

The effect of combination therapy on DVT, compared with either therapy alone was unclear (very low certainty). The large-scale (2,000 patients) PREVENT trial in 2019, Dr. Fernando noted in an interview, found that adding compression therapy to pharmacologic therapy produced no reduction in proximal lower limb DVT.

“Ultimately, I think that, even if multiple RCTs and subsequent meta-analyses were performed, at best we would find that the incremental benefit of combination therapy is very minimal,” Dr. Fernando stated.

The findings provide evidence supporting LMWH and UFH use as compared with no pharmacologic prophylaxis for prevention of DVT, according to the researchers. While a similar certainty of effect in reducing PE was not found, evidence with moderate certainty suggested that LMWH and UFH probably reduce the incidence of any VTE, compared with no pharmacologic prophylaxis. Cost-effectiveness modeling that takes into account VTE incidence supports the practice. “If you’re reducing the incidence of DVT, it’s likely you’re similarly reducing incidence of PE, though I will agree that currently the data do not support this,” he said in an interview.

Noting that, while support in existing literature for any specific agent is controversial, the authors cite that American Society of Hematology guidelines suggest considering LMWH over UFH in critically ill patients, and that their findings lend support to that position. Regarding safety, pair-wise meta-analysis did not reveal clear major bleeding incidence differences between UFH and LMWH.
 

In and out of the ICU

Concordant with studies outside the ICU finding that heparin-induced thrombocytopenia (HIT) incidence is lower among patients receiving LMWH rather than UFH for VTE prophylaxis, the meta-analysis revealed a lower incidence of HIT among the critically ill receiving LMWH, but with evidence that was of low certainty.

Uncertainty around the optimal approach to VTE prophylaxis in the ICU along with wide variations in clinical practice persist despite recognition of the issue’s importance, note Major Michael J. McMahon, MD, of Honolulu and Colonel Aaron B. Holley, MD, of Bethesda, Md., authors of an accompanying editorial, “To generalize or not to generalize? The approach to VTE prophylaxis”. They acknowledge also that the Fernando et al. analysis yields important insights into VTE prevention in the ICU. Rhetorically raising the question, “Can we now say without doubt that LMWH is the preferred agent for all patients in the ICU?” – they responded, “probably.” Not entirely eliminated, they observe, is the possibility that a specific patient subgroup may benefit from one agent compared with another. They add, “We came away more confident that LMWH should be the default choice for VTE prevention in the ICU.”

Dr. Fernando and coauthors listed multiple disclosures, but declared that they received no financial support. Dr. McMahon and Dr. Holley declared that they have no disclosures.

Compared with control treatment among critically ill adults, low-molecular-weight heparin (LMWH) reduces the incidence of deep vein thrombosis (DVT), according to a systematic review and network meta-analysis of randomized clinical trials (RCTs) published in CHEST. The analysis showed also that risk of DVT may be reduced by unfractionated heparin (UFH) and by mechanical compressive devices, although LMWH should be considered the primary pharmacologic agent for thromboprophylaxis.

Risk of venous thromboembolism (VTE), including DVT and pulmonary embolism (PE), is heightened in critically ill patients. VTE incidence is highest in major surgery and trauma patients, and mortality estimates from PE among intensive care unit patients are as high as 12%. Clinical practice guidelines recommend prophylaxis with pharmacologic agents over no prophylaxis in critically ill adults. Shannon M. Fernando, MD, of the University of Ottawa and colleagues examined the comparative efficacy and safety of various agents for VTE prophylaxis in critically ill patients through a review of 13 RCTs (9,619 patients) in six databases (Medline, PubMed, EMBASE, Scopus, Webof Science, and the Cochrane Database of Systematic Reviews). The ICU patients received a variety of therapies including pharmacologic, mechanical, or their combination for thromboprophylaxis. The control population consisted of a composite of no prophylaxis, placebo, or compression stockings only.
 

Indicative results

Analysis showed LMWH to reduce the incidence of DVT (odds ratio, 0.59; high certainty), while UFH may reduce the incidence of DVT (OR, 0.82; low certainty). Compared with UFH, LMWH probably reduces DVT (OR, 0.72; moderate certainty). Compressive devices, based on low-certainty evidence, may reduce risk of DVT, compared with control treatments (OR, 0.85).

The effect of combination therapy on DVT, compared with either therapy alone was unclear (very low certainty). The large-scale (2,000 patients) PREVENT trial in 2019, Dr. Fernando noted in an interview, found that adding compression therapy to pharmacologic therapy produced no reduction in proximal lower limb DVT.

“Ultimately, I think that, even if multiple RCTs and subsequent meta-analyses were performed, at best we would find that the incremental benefit of combination therapy is very minimal,” Dr. Fernando stated.

The findings provide evidence supporting LMWH and UFH use as compared with no pharmacologic prophylaxis for prevention of DVT, according to the researchers. While a similar certainty of effect in reducing PE was not found, evidence with moderate certainty suggested that LMWH and UFH probably reduce the incidence of any VTE, compared with no pharmacologic prophylaxis. Cost-effectiveness modeling that takes into account VTE incidence supports the practice. “If you’re reducing the incidence of DVT, it’s likely you’re similarly reducing incidence of PE, though I will agree that currently the data do not support this,” he said in an interview.

Noting that, while support in existing literature for any specific agent is controversial, the authors cite that American Society of Hematology guidelines suggest considering LMWH over UFH in critically ill patients, and that their findings lend support to that position. Regarding safety, pair-wise meta-analysis did not reveal clear major bleeding incidence differences between UFH and LMWH.
 

In and out of the ICU

Concordant with studies outside the ICU finding that heparin-induced thrombocytopenia (HIT) incidence is lower among patients receiving LMWH rather than UFH for VTE prophylaxis, the meta-analysis revealed a lower incidence of HIT among the critically ill receiving LMWH, but with evidence that was of low certainty.

Uncertainty around the optimal approach to VTE prophylaxis in the ICU along with wide variations in clinical practice persist despite recognition of the issue’s importance, note Major Michael J. McMahon, MD, of Honolulu and Colonel Aaron B. Holley, MD, of Bethesda, Md., authors of an accompanying editorial, “To generalize or not to generalize? The approach to VTE prophylaxis”. They acknowledge also that the Fernando et al. analysis yields important insights into VTE prevention in the ICU. Rhetorically raising the question, “Can we now say without doubt that LMWH is the preferred agent for all patients in the ICU?” – they responded, “probably.” Not entirely eliminated, they observe, is the possibility that a specific patient subgroup may benefit from one agent compared with another. They add, “We came away more confident that LMWH should be the default choice for VTE prevention in the ICU.”

Dr. Fernando and coauthors listed multiple disclosures, but declared that they received no financial support. Dr. McMahon and Dr. Holley declared that they have no disclosures.

What are the best tests for identification of a patient with chronic hepatitis B infection?

Continue to the answer...

Patients with chronic hepatitis B infection typically test positive for the hepatitis B surface antigen (HBsAg) and for IgG antibody to the hepatitis B core antigen (HBcAg). In addition, they also may test positive for the hepatitis B e antigen (HBeAg), and their viral load can be quantified by polymerase chain reaction (PCR) when significant antigenemia is present. The presence of the e antigen indicates a high rate of viral replication and a corresponding high rate of infectivity.

What are the best tests for identification of a patient with chronic hepatitis B infection?

Continue to the answer...

Patients with chronic hepatitis B infection typically test positive for the hepatitis B surface antigen (HBsAg) and for IgG antibody to the hepatitis B core antigen (HBcAg). In addition, they also may test positive for the hepatitis B e antigen (HBeAg), and their viral load can be quantified by polymerase chain reaction (PCR) when significant antigenemia is present. The presence of the e antigen indicates a high rate of viral replication and a corresponding high rate of infectivity.

What are the best tests for identification of a patient with chronic hepatitis B infection?

Continue to the answer...

Patients with chronic hepatitis B infection typically test positive for the hepatitis B surface antigen (HBsAg) and for IgG antibody to the hepatitis B core antigen (HBcAg). In addition, they also may test positive for the hepatitis B e antigen (HBeAg), and their viral load can be quantified by polymerase chain reaction (PCR) when significant antigenemia is present. The presence of the e antigen indicates a high rate of viral replication and a corresponding high rate of infectivity.

Atopic dermatitis (AD) is an inflammatory skin disease characterized by skin barrier disruption, skin inflammation, and pruritus.¹ It is a common and often chronic skin condition associated with the development of food allergies, asthma, and allergic rhinitis, known as the atopic march.² Atopic dermatitis is estimated to affect 10% to 25% of children, most with onset before 5 years of age, and up to 7% of adults worldwide.³ Most patients improve with time, but multiple disease trajectories are possible. Several studies have demonstrated that fewer than 4% of children develop the classic atopic march—AD followed by food allergies, asthma, and finally allergic rhinitis—with recent evidence pointing to a more complex heterogeneous progression of disease and allergic comorbidities often occurring together.^4,5 The prevalence of AD has been increasing globally over the last 30 years,⁶ with a marked increase in developed countries.^6,7 It is well accepted that AD is based on an interplay between genetic predisposition and environmental factors,⁸ but many suspect that the rapid rise in prevalence cannot be attributed to genetic factors alone.⁹ The precipitant triggers for AD remain an area of intense investigation, with ongoing debate between the “inside out” and “outside in” hypotheses; these revolve around whether abnormalities in the immune system trigger barrier dysfunction or barrier dysfunction triggers immune programming to atopy.⁸ Ongoing research related to genetic predisposition of AD has identified candidate genes implicated in both impaired skin barrier function and altered immune system pathways, further supporting that both theories may contribute to disease pathogenesis. 

The increasing prevalence of AD, with increasing disease burden within socioeconomically advantaged countries, raises the possibility of early modifiable environmental factors that may contribute to the disease process.¹⁰ Many studies point to the influence of the 21st century lifestyle and Western diet as primary contributing factors.^9,11 However, it is not clear how these factors may influence the development of allergic atopic disease. Several studies have suggested that nonheritable influences in utero can alter fetus immune function and influence the subsequent development of allergic disease.^12,13 Although many studies have examined environmental factors contributing to the development of AD in infancy and childhood, less is understood about the influence of prenatal factors. Currently, in utero exposure to tobacco smoke, phthalates, and maternal distress have been potentially implicated in the development of AD.^14,15 Several studies have examined the role of maternal diet and nutrition on the development of AD in offspring; however, formal recommendations and robust trial data are lacking. In this article, we examine the existing literature surrounding maternal diet on the development of AD in infancy and childhood.

Allergen Avoidance 

Extrapolating from the food allergy literature, it was once suggested that allergen avoidance in early childhood had a protective effect on the subsequent development of allergies; however, more recent research has found that early exposure to common food allergens, such as peanuts or eggs, may actually reduce a child’s risk for developing these allergies later in life.¹⁶ Among infants at high risk for food allergy, sustained consumption of peanut products beginning in the first 11 months of life resulted in an 81% lower rate of peanut allergy at 60 months of age than the rate among children who avoided peanuts.¹⁷ Given the results that antigen avoidance during infancy/childhood does not protect against the development of allergies and may actually be counterproductive, it is not surprising that research studying antigen avoidance during pregnancy on the development of AD also has demonstrated limited efficacy. A systematic review of 5 trials on maternal dietary antigen avoidance (N=952) suggested no protective effects of avoiding antigenic foods during pregnancy on the development of AD in the first 18 months of life.¹⁸ Another meta-analysis evaluating 12 intervention trials looked at the effects of maternal allergenic food avoidance during pregnancy or lactation and found no reduced risk for subsequent development of allergic disease, including AD.¹⁹ The American Academy of Pediatrics 2019 consensus statement does not support maternal dietary restrictions in pregnancy for the prevention of atopic disease and makes note that the data remain limited, which complicates drawing any firm conclusions.²⁰

Probiotic Supplementation 

One of the most investigated dietary supplements for the prevention of atopic disease is probiotics, with possible benefits noted in both the prenatal and postnatal periods. Baquerizo Nole et al²¹ examined several studies looking at the various benefits of probiotics in AD, which included inhibition of the helper T cell (T_H2) response, stimulation of the T_H1 response, upregulation of regulatory T cells, acceleration of skin and mucosal barrier function, increase in intestinal microflora diversity, suppression of toxic fermentation products in the intestinal lumen from increased production of short-chain fatty acids, and inhibition of Staphylococcus aureus attachment on epidermal keratinocytes. It is unclear how this may affect infants prenatally; however, transfer of maternal intestinal microflora during delivery and shortly thereafter has demonstrated that probiotic strains remain detectable in the infant’s stool up to 6 months after delivery, even if the mother has discontinued use.²² A 2008 meta-analysis of 10 double-bind, randomized, controlled trials (N=1880) looking at the use of maternal prenatal and postnatal probiotic supplementation in the prevention of pediatric AD found a relative risk (RR) ratio of 0.69 (95% CI, 0.57-0.83) using a fixed effects model and RR ratio of 0.66 (95% CI, 0.49-0.89) using a random effects model. After exclusion of one study that evaluated the effect of postnatal probiotic supplementation only, the RR ratio decreased to 0.61 for both the fixed effects and random effects models.²³ A systematic review by Panduru et al²⁴ noted similar findings with a subgroup meta-analysis of 11 studies of prenatal supplementation followed by postnatal supplementation of probiotics, which demonstrated a protective effect on the development of AD (odds ratio [OR]=0.61, P<.001). Postnatal supplementation alone (4 studies) did not have the same association (OR=0.95, P<.82).²⁴ A 2012 meta-analysis by Doege et al²⁵ evaluated 7 randomized, double-blinded, placebo-controlled trials that assessed probiotic supplementation during pregnancy (without incorporation of postnatal supplementation) and found a significant risk reduction of 5.7% (P=.022) for AD in children aged 2 to 7 years. Interestingly, this was only significant for Lactobacillus and not for other bacterial strains, even if a mixture of strains included Lactobacillus. However, Panduru et al²⁴ found both maternal Lactobacillus supplementation alone (8 studies) and in combination with Bifidobacterium (9 studies) was protective against AD development in children (OR=0.70, P=.004; OR=0.62, P<.001). A more recent 2015 meta-analysis of 17 studies (N=4755) evaluating the use of maternal probiotic supplementation in pregnancy and/or through the infant’s first 3 months of life found a significantly lower RR (0.78 [95% CI, 0.69-0.89], P=.0003) for the development of AD in infants treated with probiotics and found this risk to be even further decreased when a mixture of probiotics including both Lactobacillus and Bifidobacterium was used (RR=0.54 [95% CI, 0.43-0.68], P<.00001).²⁶

Antioxidants

The Westernization of many developing countries’ diets—diets high in saturated fats, protein, sucrose, salt, and processed foods and low in fresh fruits and green vegetables—has led to a reduced intake of antioxidants and an increase in susceptibility to oxidative damage.^27,28 One hypothesis suggests that a reduction in nutritional antioxidants and subsequent oxidative damage leads to airway inflammation that may contribute to an increased prevalence of asthma.²⁷ In vitro data suggest that antioxidant deficiency may influence the differentiation of helper T cells to a T_H2 phenotype, which can increase susceptibility to the development of asthma and allergies.²⁹ Vitamin E specifically has been shown to inhibit IL-4 gene expression, which drives type 2 immunity and decreases expression of multiple genes that regulate epidermal barrier function, subsequently increasing susceptibility to allergic inflammation and AD.^29,30 Regardless of the proposed mechanisms for antioxidant deficiency increasing susceptibility to allergic disease, studies evaluating the benefits of antioxidant intake during pregnancy in relation to AD have not been promising. Several studies have found no association between prenatal vitamin E intake and the risk for AD development in infants and children.^31,32 Another study found a statistically significant inverse relationship between vitamin E intake in mothers with a history of atopy and the development of AD in their children at 2 years of age but not at 1 year of age (P-trend=.024).³³ It has been suggested that varying vitamin E isoforms may contribute to the discrepant results previously discussed, with the γ-tocopherol isoform (found frequently in Westernized diets)³⁴ as a driver of inflammation in murine models.³⁵ West et al³¹ noted an association between vitamin C intake and development of “any allergic disease”—AD, IgE-mediated food allergy, or asthma—with a crude OR of 0.48 (95% CI, 0.25-0.93). However, the P-trend and adjusted OR were not statistically significant. The investigators found no association between maternal intake of beta-carotene, vitamin E, or zinc, but they did find copper supplementation to be protective on the development of AD at 1 year of age (P-trend=0.03). Interestingly, when the data for total antioxidant intake—vitamin C, vitamin E, zinc, beta-carotene, and copper from both diet and supplementation—were combined and analyzed, no statistically significant associations for any of the antioxidants were found.³¹ Another study of 763 Japanese mother-child pairs found a reduced risk for AD at 16 to 24 months of age with high maternal intake of beta-carotene but found no statistically significant exposure-response associations with other antioxidants, including alpha-carotene, vitamin C, or zinc from dietary intake alone.³² These results were substantiated by 2 meta-analyses evaluating a total of 93 combined intervention trials and cohorts where no association was found between vitamin or mineral intake during pregnancy and/or during infancy and the development of AD.^19,36 

Fatty Acids 

Other dietary changes that are associated with an increased prevalence of atopic diseases in children include excess consumption of omega-6 (n-6) long-chain polyunsaturated fatty acids (LC-PUFA) and insufficient omega-3 (n-3) LC-PUFA consumption.³⁷ Given prior evidence that allergic immune responses in infants may be primed before birth,³⁸ researchers have questioned whether the anti-inflammatory properties of n-3 LC-PUFA when supplemented during pregnancy may have immunomodulatory effects on infants that could alter their predisposition to develop allergic disease, including AD.³⁹ A systematic review and meta-analysis of randomized controlled trials found a statistically significant RR of 0.53 (95% CI, 0.35-0.81; P=.004) for the incidence of AD at 12 months of age with maternal supplementation of n-3 LC-PUFA.⁹ Another trial of 145 pregnant women randomized to supplementation with fish oil vs placebo starting at gestational week 25 and continuing through 3.5 months of breastfeeding found a reduced cumulative incidence of AD in the intervention group compared to controls at 2 years of age, with a statistically significant crude OR of 0.33 (95% CI, 0.11-0.97; P=.04).⁴⁰ However, the adjusted OR was not statistically significant. In addition, they found that mothers and infants with higher proportions of docosahexaenoic acid and eicosapentaenoic acid in plasma phospholipids have been noted to have a lower prevalence of IgE-associated disease in a dose-dependent manner (P<.05 and P<.05, respectively).⁴⁰ In another trial of 98 pregnant women randomized to fish oil supplementation or placebo from 20 weeks’ gestation to delivery found no difference in the frequency of AD but did note that infants in the exposure group had significantly less severe AD compared to controls (OR=0.09 [95% CI, 0.1-0.94]; P=.045).³⁹ A prospective birth cohort study of 2641 children evaluated dietary composition during the last 4 weeks of pregnancy and found that consumption of foods rich in n-6 LC-PUFAs (eg, margarine, vegetable oil) increased the risk for developing AD, while foods rich in n-3 LC-PUFAs (eg, fish) decreased the risk for developing AD in offspring at 2 years of age. All P values for margarine, vegetable oil, and fish were statistically significant on logistic regression at P<.05.⁴¹ A longitudinal analysis of follow-up data from a randomized controlled trial looking at maternal prenatal n-3 LC-PUFA intake and the development of allergic disease (including AD) found no differences in the development of disease at 1-, 3-, or 6-year follow-up.⁴² Despite several studies demonstrating a possible benefit of omega-3 fatty acid intake on the development of AD in offspring, the longitudinal analysis by Best et al⁴² reminds us that long-term follow-up is critical in establishing benefit of any intervention given the heterogeneous and progressive nature of the atopic march and AD. 

Specific Diets 

Several studies have evaluated the role of dietary patterns and their influence on atopic disease. Studies evaluating dietary patterns or supplement intake can be challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Further, analysis of any one food group does not account for the potential interplay between nutrients.⁴³ Studies should focus more on dietary patterns vs individual foods to assess true risk.^43,44 Given these limitations, study results on diet should be carefully scrutinized; however, there are still some positive findings that deserve further investigation. Chatzi et al⁴⁴ followed 460 children for 6.5 years and found a protective effect for the development of atopy in the offspring of women who had high adherence to the Mediterranean diet (OR 0.55 [95% CI, 0.31-0.97]). Another cohort study evaluating the effects of the Mediterranean diet and risk for AD in the first year of life in 2516 mother-child pairs from Spain and Greece found no statistically significant association with consumption of the Mediterranean diet and AD. The investigators also evaluated intake of fruits, nuts, vegetables, meats, processed meats, dairy products, and cereal and found no statistically significant protective benefit.⁴⁵ Another systematic review of more than 90 observational studies identified no significant relationship between prenatal dietary exposures of fruits, vegetables, nuts, fat, fatty acids, eggs, cereal, milk, alcohol, tea, or coffee and risk for allergic disease in offspring, including AD.¹⁹

A Chinese prospective cohort study evaluated the dietary protein patterns of 713 mother-child pairs and the incidence of infant AD at 6 months of age.⁴⁶ Dietary protein patterns were characterized as predominantly poultry, plant based, dairy and eggs, and red meat and fish. The investigators found a statistically significant reduced risk for AD in mothers who consumed plant-based or dairy and eggs protein patterns when compared to a poultry protein pattern with an adjusted OR of 0.572 (95% CI, 0.330-0.992) and 0.478 (95% CI, 0.274-0.837), respectively. This protective effect was not seen with the red meat and fish protein patterns.⁴⁶ Similar results were seen in a 2020 Canadian study that evaluated the effects of a Western (fats, meats, processed foods, and starchy vegetables), balanced (diverse sources of animal proteins [especially fish], fruits, vegetables, nuts, and seeds), or plant-based (dairy, legumes, vegetables, whole grains, and an aversion to meats) diet in more than 2000 mother-infant pairs from 24 to 28 weeks’ gestation to 1 year of age. The investigators found a lower OR of AD in mothers who followed a mostly plant-based diet compared to other dietary patterns (OR 0.65 [95% CI, 0.55-0.76]; P<.001).¹⁰ Another prospective Japanese study looking at healthy (high intake of green and yellow vegetables, seaweed, mushrooms, white vegetables, pulses, potatoes, fish, sea products, fruit, and shellfish, and low intake of confectioneries and soft drinks), Western (high intake of vegetable oil, salt-containing seasonings, beef, pork, processed meat, eggs, chicken, and white vegetables, and low intake of fruit, soft drinks, and confectioneries), or Japanese (high intake of rice, miso soup, sea products, and fish, and low intake of bread, confectioneries, and dairy products) dietary patterns in 763 mother-child pairs found no association between diet during pregnancy and development of AD in offspring at 16 to 24 months.⁴⁷ Unfortunately, a longitudinal data analysis has not been performed for this study.

Final Thoughts

Atopic dermatitis is a complex, progressive, and heterogeneous disease with both genetic and environmental influences. Studying the effects of diet on the development, progression, or severity of disease can be very difficult due to the heterogeneity of study designs, lack of long-term follow-up, and high potential for residual confounding. Studies evaluating dietary patterns or supplement intake can be equally challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Very few studies have looked specifically at maternal dietary composition and the development of AD alone (without inclusion of asthma or food allergy). Ultimately, the inconsistency of the data makes it difficult to draw conclusions and make formal recommendations for this vulnerable population. Additional evidence from well-powered trials with comparable methodology and objective outcome measures will be imperative to make formal recommendations. In addition, longitudinal follow-up will be essential to determine long-term benefit and influence on the atopic march.

Atopic dermatitis (AD) is an inflammatory skin disease characterized by skin barrier disruption, skin inflammation, and pruritus.¹ It is a common and often chronic skin condition associated with the development of food allergies, asthma, and allergic rhinitis, known as the atopic march.² Atopic dermatitis is estimated to affect 10% to 25% of children, most with onset before 5 years of age, and up to 7% of adults worldwide.³ Most patients improve with time, but multiple disease trajectories are possible. Several studies have demonstrated that fewer than 4% of children develop the classic atopic march—AD followed by food allergies, asthma, and finally allergic rhinitis—with recent evidence pointing to a more complex heterogeneous progression of disease and allergic comorbidities often occurring together.^4,5 The prevalence of AD has been increasing globally over the last 30 years,⁶ with a marked increase in developed countries.^6,7 It is well accepted that AD is based on an interplay between genetic predisposition and environmental factors,⁸ but many suspect that the rapid rise in prevalence cannot be attributed to genetic factors alone.⁹ The precipitant triggers for AD remain an area of intense investigation, with ongoing debate between the “inside out” and “outside in” hypotheses; these revolve around whether abnormalities in the immune system trigger barrier dysfunction or barrier dysfunction triggers immune programming to atopy.⁸ Ongoing research related to genetic predisposition of AD has identified candidate genes implicated in both impaired skin barrier function and altered immune system pathways, further supporting that both theories may contribute to disease pathogenesis. 

The increasing prevalence of AD, with increasing disease burden within socioeconomically advantaged countries, raises the possibility of early modifiable environmental factors that may contribute to the disease process.¹⁰ Many studies point to the influence of the 21st century lifestyle and Western diet as primary contributing factors.^9,11 However, it is not clear how these factors may influence the development of allergic atopic disease. Several studies have suggested that nonheritable influences in utero can alter fetus immune function and influence the subsequent development of allergic disease.^12,13 Although many studies have examined environmental factors contributing to the development of AD in infancy and childhood, less is understood about the influence of prenatal factors. Currently, in utero exposure to tobacco smoke, phthalates, and maternal distress have been potentially implicated in the development of AD.^14,15 Several studies have examined the role of maternal diet and nutrition on the development of AD in offspring; however, formal recommendations and robust trial data are lacking. In this article, we examine the existing literature surrounding maternal diet on the development of AD in infancy and childhood.

Allergen Avoidance 

Extrapolating from the food allergy literature, it was once suggested that allergen avoidance in early childhood had a protective effect on the subsequent development of allergies; however, more recent research has found that early exposure to common food allergens, such as peanuts or eggs, may actually reduce a child’s risk for developing these allergies later in life.¹⁶ Among infants at high risk for food allergy, sustained consumption of peanut products beginning in the first 11 months of life resulted in an 81% lower rate of peanut allergy at 60 months of age than the rate among children who avoided peanuts.¹⁷ Given the results that antigen avoidance during infancy/childhood does not protect against the development of allergies and may actually be counterproductive, it is not surprising that research studying antigen avoidance during pregnancy on the development of AD also has demonstrated limited efficacy. A systematic review of 5 trials on maternal dietary antigen avoidance (N=952) suggested no protective effects of avoiding antigenic foods during pregnancy on the development of AD in the first 18 months of life.¹⁸ Another meta-analysis evaluating 12 intervention trials looked at the effects of maternal allergenic food avoidance during pregnancy or lactation and found no reduced risk for subsequent development of allergic disease, including AD.¹⁹ The American Academy of Pediatrics 2019 consensus statement does not support maternal dietary restrictions in pregnancy for the prevention of atopic disease and makes note that the data remain limited, which complicates drawing any firm conclusions.²⁰

Probiotic Supplementation 

One of the most investigated dietary supplements for the prevention of atopic disease is probiotics, with possible benefits noted in both the prenatal and postnatal periods. Baquerizo Nole et al²¹ examined several studies looking at the various benefits of probiotics in AD, which included inhibition of the helper T cell (T_H2) response, stimulation of the T_H1 response, upregulation of regulatory T cells, acceleration of skin and mucosal barrier function, increase in intestinal microflora diversity, suppression of toxic fermentation products in the intestinal lumen from increased production of short-chain fatty acids, and inhibition of Staphylococcus aureus attachment on epidermal keratinocytes. It is unclear how this may affect infants prenatally; however, transfer of maternal intestinal microflora during delivery and shortly thereafter has demonstrated that probiotic strains remain detectable in the infant’s stool up to 6 months after delivery, even if the mother has discontinued use.²² A 2008 meta-analysis of 10 double-bind, randomized, controlled trials (N=1880) looking at the use of maternal prenatal and postnatal probiotic supplementation in the prevention of pediatric AD found a relative risk (RR) ratio of 0.69 (95% CI, 0.57-0.83) using a fixed effects model and RR ratio of 0.66 (95% CI, 0.49-0.89) using a random effects model. After exclusion of one study that evaluated the effect of postnatal probiotic supplementation only, the RR ratio decreased to 0.61 for both the fixed effects and random effects models.²³ A systematic review by Panduru et al²⁴ noted similar findings with a subgroup meta-analysis of 11 studies of prenatal supplementation followed by postnatal supplementation of probiotics, which demonstrated a protective effect on the development of AD (odds ratio [OR]=0.61, P<.001). Postnatal supplementation alone (4 studies) did not have the same association (OR=0.95, P<.82).²⁴ A 2012 meta-analysis by Doege et al²⁵ evaluated 7 randomized, double-blinded, placebo-controlled trials that assessed probiotic supplementation during pregnancy (without incorporation of postnatal supplementation) and found a significant risk reduction of 5.7% (P=.022) for AD in children aged 2 to 7 years. Interestingly, this was only significant for Lactobacillus and not for other bacterial strains, even if a mixture of strains included Lactobacillus. However, Panduru et al²⁴ found both maternal Lactobacillus supplementation alone (8 studies) and in combination with Bifidobacterium (9 studies) was protective against AD development in children (OR=0.70, P=.004; OR=0.62, P<.001). A more recent 2015 meta-analysis of 17 studies (N=4755) evaluating the use of maternal probiotic supplementation in pregnancy and/or through the infant’s first 3 months of life found a significantly lower RR (0.78 [95% CI, 0.69-0.89], P=.0003) for the development of AD in infants treated with probiotics and found this risk to be even further decreased when a mixture of probiotics including both Lactobacillus and Bifidobacterium was used (RR=0.54 [95% CI, 0.43-0.68], P<.00001).²⁶

Antioxidants

The Westernization of many developing countries’ diets—diets high in saturated fats, protein, sucrose, salt, and processed foods and low in fresh fruits and green vegetables—has led to a reduced intake of antioxidants and an increase in susceptibility to oxidative damage.^27,28 One hypothesis suggests that a reduction in nutritional antioxidants and subsequent oxidative damage leads to airway inflammation that may contribute to an increased prevalence of asthma.²⁷ In vitro data suggest that antioxidant deficiency may influence the differentiation of helper T cells to a T_H2 phenotype, which can increase susceptibility to the development of asthma and allergies.²⁹ Vitamin E specifically has been shown to inhibit IL-4 gene expression, which drives type 2 immunity and decreases expression of multiple genes that regulate epidermal barrier function, subsequently increasing susceptibility to allergic inflammation and AD.^29,30 Regardless of the proposed mechanisms for antioxidant deficiency increasing susceptibility to allergic disease, studies evaluating the benefits of antioxidant intake during pregnancy in relation to AD have not been promising. Several studies have found no association between prenatal vitamin E intake and the risk for AD development in infants and children.^31,32 Another study found a statistically significant inverse relationship between vitamin E intake in mothers with a history of atopy and the development of AD in their children at 2 years of age but not at 1 year of age (P-trend=.024).³³ It has been suggested that varying vitamin E isoforms may contribute to the discrepant results previously discussed, with the γ-tocopherol isoform (found frequently in Westernized diets)³⁴ as a driver of inflammation in murine models.³⁵ West et al³¹ noted an association between vitamin C intake and development of “any allergic disease”—AD, IgE-mediated food allergy, or asthma—with a crude OR of 0.48 (95% CI, 0.25-0.93). However, the P-trend and adjusted OR were not statistically significant. The investigators found no association between maternal intake of beta-carotene, vitamin E, or zinc, but they did find copper supplementation to be protective on the development of AD at 1 year of age (P-trend=0.03). Interestingly, when the data for total antioxidant intake—vitamin C, vitamin E, zinc, beta-carotene, and copper from both diet and supplementation—were combined and analyzed, no statistically significant associations for any of the antioxidants were found.³¹ Another study of 763 Japanese mother-child pairs found a reduced risk for AD at 16 to 24 months of age with high maternal intake of beta-carotene but found no statistically significant exposure-response associations with other antioxidants, including alpha-carotene, vitamin C, or zinc from dietary intake alone.³² These results were substantiated by 2 meta-analyses evaluating a total of 93 combined intervention trials and cohorts where no association was found between vitamin or mineral intake during pregnancy and/or during infancy and the development of AD.^19,36 

Fatty Acids 

Other dietary changes that are associated with an increased prevalence of atopic diseases in children include excess consumption of omega-6 (n-6) long-chain polyunsaturated fatty acids (LC-PUFA) and insufficient omega-3 (n-3) LC-PUFA consumption.³⁷ Given prior evidence that allergic immune responses in infants may be primed before birth,³⁸ researchers have questioned whether the anti-inflammatory properties of n-3 LC-PUFA when supplemented during pregnancy may have immunomodulatory effects on infants that could alter their predisposition to develop allergic disease, including AD.³⁹ A systematic review and meta-analysis of randomized controlled trials found a statistically significant RR of 0.53 (95% CI, 0.35-0.81; P=.004) for the incidence of AD at 12 months of age with maternal supplementation of n-3 LC-PUFA.⁹ Another trial of 145 pregnant women randomized to supplementation with fish oil vs placebo starting at gestational week 25 and continuing through 3.5 months of breastfeeding found a reduced cumulative incidence of AD in the intervention group compared to controls at 2 years of age, with a statistically significant crude OR of 0.33 (95% CI, 0.11-0.97; P=.04).⁴⁰ However, the adjusted OR was not statistically significant. In addition, they found that mothers and infants with higher proportions of docosahexaenoic acid and eicosapentaenoic acid in plasma phospholipids have been noted to have a lower prevalence of IgE-associated disease in a dose-dependent manner (P<.05 and P<.05, respectively).⁴⁰ In another trial of 98 pregnant women randomized to fish oil supplementation or placebo from 20 weeks’ gestation to delivery found no difference in the frequency of AD but did note that infants in the exposure group had significantly less severe AD compared to controls (OR=0.09 [95% CI, 0.1-0.94]; P=.045).³⁹ A prospective birth cohort study of 2641 children evaluated dietary composition during the last 4 weeks of pregnancy and found that consumption of foods rich in n-6 LC-PUFAs (eg, margarine, vegetable oil) increased the risk for developing AD, while foods rich in n-3 LC-PUFAs (eg, fish) decreased the risk for developing AD in offspring at 2 years of age. All P values for margarine, vegetable oil, and fish were statistically significant on logistic regression at P<.05.⁴¹ A longitudinal analysis of follow-up data from a randomized controlled trial looking at maternal prenatal n-3 LC-PUFA intake and the development of allergic disease (including AD) found no differences in the development of disease at 1-, 3-, or 6-year follow-up.⁴² Despite several studies demonstrating a possible benefit of omega-3 fatty acid intake on the development of AD in offspring, the longitudinal analysis by Best et al⁴² reminds us that long-term follow-up is critical in establishing benefit of any intervention given the heterogeneous and progressive nature of the atopic march and AD. 

Specific Diets 

Several studies have evaluated the role of dietary patterns and their influence on atopic disease. Studies evaluating dietary patterns or supplement intake can be challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Further, analysis of any one food group does not account for the potential interplay between nutrients.⁴³ Studies should focus more on dietary patterns vs individual foods to assess true risk.^43,44 Given these limitations, study results on diet should be carefully scrutinized; however, there are still some positive findings that deserve further investigation. Chatzi et al⁴⁴ followed 460 children for 6.5 years and found a protective effect for the development of atopy in the offspring of women who had high adherence to the Mediterranean diet (OR 0.55 [95% CI, 0.31-0.97]). Another cohort study evaluating the effects of the Mediterranean diet and risk for AD in the first year of life in 2516 mother-child pairs from Spain and Greece found no statistically significant association with consumption of the Mediterranean diet and AD. The investigators also evaluated intake of fruits, nuts, vegetables, meats, processed meats, dairy products, and cereal and found no statistically significant protective benefit.⁴⁵ Another systematic review of more than 90 observational studies identified no significant relationship between prenatal dietary exposures of fruits, vegetables, nuts, fat, fatty acids, eggs, cereal, milk, alcohol, tea, or coffee and risk for allergic disease in offspring, including AD.¹⁹

A Chinese prospective cohort study evaluated the dietary protein patterns of 713 mother-child pairs and the incidence of infant AD at 6 months of age.⁴⁶ Dietary protein patterns were characterized as predominantly poultry, plant based, dairy and eggs, and red meat and fish. The investigators found a statistically significant reduced risk for AD in mothers who consumed plant-based or dairy and eggs protein patterns when compared to a poultry protein pattern with an adjusted OR of 0.572 (95% CI, 0.330-0.992) and 0.478 (95% CI, 0.274-0.837), respectively. This protective effect was not seen with the red meat and fish protein patterns.⁴⁶ Similar results were seen in a 2020 Canadian study that evaluated the effects of a Western (fats, meats, processed foods, and starchy vegetables), balanced (diverse sources of animal proteins [especially fish], fruits, vegetables, nuts, and seeds), or plant-based (dairy, legumes, vegetables, whole grains, and an aversion to meats) diet in more than 2000 mother-infant pairs from 24 to 28 weeks’ gestation to 1 year of age. The investigators found a lower OR of AD in mothers who followed a mostly plant-based diet compared to other dietary patterns (OR 0.65 [95% CI, 0.55-0.76]; P<.001).¹⁰ Another prospective Japanese study looking at healthy (high intake of green and yellow vegetables, seaweed, mushrooms, white vegetables, pulses, potatoes, fish, sea products, fruit, and shellfish, and low intake of confectioneries and soft drinks), Western (high intake of vegetable oil, salt-containing seasonings, beef, pork, processed meat, eggs, chicken, and white vegetables, and low intake of fruit, soft drinks, and confectioneries), or Japanese (high intake of rice, miso soup, sea products, and fish, and low intake of bread, confectioneries, and dairy products) dietary patterns in 763 mother-child pairs found no association between diet during pregnancy and development of AD in offspring at 16 to 24 months.⁴⁷ Unfortunately, a longitudinal data analysis has not been performed for this study.

Final Thoughts

Atopic dermatitis is a complex, progressive, and heterogeneous disease with both genetic and environmental influences. Studying the effects of diet on the development, progression, or severity of disease can be very difficult due to the heterogeneity of study designs, lack of long-term follow-up, and high potential for residual confounding. Studies evaluating dietary patterns or supplement intake can be equally challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Very few studies have looked specifically at maternal dietary composition and the development of AD alone (without inclusion of asthma or food allergy). Ultimately, the inconsistency of the data makes it difficult to draw conclusions and make formal recommendations for this vulnerable population. Additional evidence from well-powered trials with comparable methodology and objective outcome measures will be imperative to make formal recommendations. In addition, longitudinal follow-up will be essential to determine long-term benefit and influence on the atopic march.

Atopic dermatitis (AD) is an inflammatory skin disease characterized by skin barrier disruption, skin inflammation, and pruritus.¹ It is a common and often chronic skin condition associated with the development of food allergies, asthma, and allergic rhinitis, known as the atopic march.² Atopic dermatitis is estimated to affect 10% to 25% of children, most with onset before 5 years of age, and up to 7% of adults worldwide.³ Most patients improve with time, but multiple disease trajectories are possible. Several studies have demonstrated that fewer than 4% of children develop the classic atopic march—AD followed by food allergies, asthma, and finally allergic rhinitis—with recent evidence pointing to a more complex heterogeneous progression of disease and allergic comorbidities often occurring together.^4,5 The prevalence of AD has been increasing globally over the last 30 years,⁶ with a marked increase in developed countries.^6,7 It is well accepted that AD is based on an interplay between genetic predisposition and environmental factors,⁸ but many suspect that the rapid rise in prevalence cannot be attributed to genetic factors alone.⁹ The precipitant triggers for AD remain an area of intense investigation, with ongoing debate between the “inside out” and “outside in” hypotheses; these revolve around whether abnormalities in the immune system trigger barrier dysfunction or barrier dysfunction triggers immune programming to atopy.⁸ Ongoing research related to genetic predisposition of AD has identified candidate genes implicated in both impaired skin barrier function and altered immune system pathways, further supporting that both theories may contribute to disease pathogenesis. 

The increasing prevalence of AD, with increasing disease burden within socioeconomically advantaged countries, raises the possibility of early modifiable environmental factors that may contribute to the disease process.¹⁰ Many studies point to the influence of the 21st century lifestyle and Western diet as primary contributing factors.^9,11 However, it is not clear how these factors may influence the development of allergic atopic disease. Several studies have suggested that nonheritable influences in utero can alter fetus immune function and influence the subsequent development of allergic disease.^12,13 Although many studies have examined environmental factors contributing to the development of AD in infancy and childhood, less is understood about the influence of prenatal factors. Currently, in utero exposure to tobacco smoke, phthalates, and maternal distress have been potentially implicated in the development of AD.^14,15 Several studies have examined the role of maternal diet and nutrition on the development of AD in offspring; however, formal recommendations and robust trial data are lacking. In this article, we examine the existing literature surrounding maternal diet on the development of AD in infancy and childhood.

Allergen Avoidance 

Extrapolating from the food allergy literature, it was once suggested that allergen avoidance in early childhood had a protective effect on the subsequent development of allergies; however, more recent research has found that early exposure to common food allergens, such as peanuts or eggs, may actually reduce a child’s risk for developing these allergies later in life.¹⁶ Among infants at high risk for food allergy, sustained consumption of peanut products beginning in the first 11 months of life resulted in an 81% lower rate of peanut allergy at 60 months of age than the rate among children who avoided peanuts.¹⁷ Given the results that antigen avoidance during infancy/childhood does not protect against the development of allergies and may actually be counterproductive, it is not surprising that research studying antigen avoidance during pregnancy on the development of AD also has demonstrated limited efficacy. A systematic review of 5 trials on maternal dietary antigen avoidance (N=952) suggested no protective effects of avoiding antigenic foods during pregnancy on the development of AD in the first 18 months of life.¹⁸ Another meta-analysis evaluating 12 intervention trials looked at the effects of maternal allergenic food avoidance during pregnancy or lactation and found no reduced risk for subsequent development of allergic disease, including AD.¹⁹ The American Academy of Pediatrics 2019 consensus statement does not support maternal dietary restrictions in pregnancy for the prevention of atopic disease and makes note that the data remain limited, which complicates drawing any firm conclusions.²⁰

Probiotic Supplementation 

One of the most investigated dietary supplements for the prevention of atopic disease is probiotics, with possible benefits noted in both the prenatal and postnatal periods. Baquerizo Nole et al²¹ examined several studies looking at the various benefits of probiotics in AD, which included inhibition of the helper T cell (T_H2) response, stimulation of the T_H1 response, upregulation of regulatory T cells, acceleration of skin and mucosal barrier function, increase in intestinal microflora diversity, suppression of toxic fermentation products in the intestinal lumen from increased production of short-chain fatty acids, and inhibition of Staphylococcus aureus attachment on epidermal keratinocytes. It is unclear how this may affect infants prenatally; however, transfer of maternal intestinal microflora during delivery and shortly thereafter has demonstrated that probiotic strains remain detectable in the infant’s stool up to 6 months after delivery, even if the mother has discontinued use.²² A 2008 meta-analysis of 10 double-bind, randomized, controlled trials (N=1880) looking at the use of maternal prenatal and postnatal probiotic supplementation in the prevention of pediatric AD found a relative risk (RR) ratio of 0.69 (95% CI, 0.57-0.83) using a fixed effects model and RR ratio of 0.66 (95% CI, 0.49-0.89) using a random effects model. After exclusion of one study that evaluated the effect of postnatal probiotic supplementation only, the RR ratio decreased to 0.61 for both the fixed effects and random effects models.²³ A systematic review by Panduru et al²⁴ noted similar findings with a subgroup meta-analysis of 11 studies of prenatal supplementation followed by postnatal supplementation of probiotics, which demonstrated a protective effect on the development of AD (odds ratio [OR]=0.61, P<.001). Postnatal supplementation alone (4 studies) did not have the same association (OR=0.95, P<.82).²⁴ A 2012 meta-analysis by Doege et al²⁵ evaluated 7 randomized, double-blinded, placebo-controlled trials that assessed probiotic supplementation during pregnancy (without incorporation of postnatal supplementation) and found a significant risk reduction of 5.7% (P=.022) for AD in children aged 2 to 7 years. Interestingly, this was only significant for Lactobacillus and not for other bacterial strains, even if a mixture of strains included Lactobacillus. However, Panduru et al²⁴ found both maternal Lactobacillus supplementation alone (8 studies) and in combination with Bifidobacterium (9 studies) was protective against AD development in children (OR=0.70, P=.004; OR=0.62, P<.001). A more recent 2015 meta-analysis of 17 studies (N=4755) evaluating the use of maternal probiotic supplementation in pregnancy and/or through the infant’s first 3 months of life found a significantly lower RR (0.78 [95% CI, 0.69-0.89], P=.0003) for the development of AD in infants treated with probiotics and found this risk to be even further decreased when a mixture of probiotics including both Lactobacillus and Bifidobacterium was used (RR=0.54 [95% CI, 0.43-0.68], P<.00001).²⁶

Antioxidants

The Westernization of many developing countries’ diets—diets high in saturated fats, protein, sucrose, salt, and processed foods and low in fresh fruits and green vegetables—has led to a reduced intake of antioxidants and an increase in susceptibility to oxidative damage.^27,28 One hypothesis suggests that a reduction in nutritional antioxidants and subsequent oxidative damage leads to airway inflammation that may contribute to an increased prevalence of asthma.²⁷ In vitro data suggest that antioxidant deficiency may influence the differentiation of helper T cells to a T_H2 phenotype, which can increase susceptibility to the development of asthma and allergies.²⁹ Vitamin E specifically has been shown to inhibit IL-4 gene expression, which drives type 2 immunity and decreases expression of multiple genes that regulate epidermal barrier function, subsequently increasing susceptibility to allergic inflammation and AD.^29,30 Regardless of the proposed mechanisms for antioxidant deficiency increasing susceptibility to allergic disease, studies evaluating the benefits of antioxidant intake during pregnancy in relation to AD have not been promising. Several studies have found no association between prenatal vitamin E intake and the risk for AD development in infants and children.^31,32 Another study found a statistically significant inverse relationship between vitamin E intake in mothers with a history of atopy and the development of AD in their children at 2 years of age but not at 1 year of age (P-trend=.024).³³ It has been suggested that varying vitamin E isoforms may contribute to the discrepant results previously discussed, with the γ-tocopherol isoform (found frequently in Westernized diets)³⁴ as a driver of inflammation in murine models.³⁵ West et al³¹ noted an association between vitamin C intake and development of “any allergic disease”—AD, IgE-mediated food allergy, or asthma—with a crude OR of 0.48 (95% CI, 0.25-0.93). However, the P-trend and adjusted OR were not statistically significant. The investigators found no association between maternal intake of beta-carotene, vitamin E, or zinc, but they did find copper supplementation to be protective on the development of AD at 1 year of age (P-trend=0.03). Interestingly, when the data for total antioxidant intake—vitamin C, vitamin E, zinc, beta-carotene, and copper from both diet and supplementation—were combined and analyzed, no statistically significant associations for any of the antioxidants were found.³¹ Another study of 763 Japanese mother-child pairs found a reduced risk for AD at 16 to 24 months of age with high maternal intake of beta-carotene but found no statistically significant exposure-response associations with other antioxidants, including alpha-carotene, vitamin C, or zinc from dietary intake alone.³² These results were substantiated by 2 meta-analyses evaluating a total of 93 combined intervention trials and cohorts where no association was found between vitamin or mineral intake during pregnancy and/or during infancy and the development of AD.^19,36 

Fatty Acids 

Other dietary changes that are associated with an increased prevalence of atopic diseases in children include excess consumption of omega-6 (n-6) long-chain polyunsaturated fatty acids (LC-PUFA) and insufficient omega-3 (n-3) LC-PUFA consumption.³⁷ Given prior evidence that allergic immune responses in infants may be primed before birth,³⁸ researchers have questioned whether the anti-inflammatory properties of n-3 LC-PUFA when supplemented during pregnancy may have immunomodulatory effects on infants that could alter their predisposition to develop allergic disease, including AD.³⁹ A systematic review and meta-analysis of randomized controlled trials found a statistically significant RR of 0.53 (95% CI, 0.35-0.81; P=.004) for the incidence of AD at 12 months of age with maternal supplementation of n-3 LC-PUFA.⁹ Another trial of 145 pregnant women randomized to supplementation with fish oil vs placebo starting at gestational week 25 and continuing through 3.5 months of breastfeeding found a reduced cumulative incidence of AD in the intervention group compared to controls at 2 years of age, with a statistically significant crude OR of 0.33 (95% CI, 0.11-0.97; P=.04).⁴⁰ However, the adjusted OR was not statistically significant. In addition, they found that mothers and infants with higher proportions of docosahexaenoic acid and eicosapentaenoic acid in plasma phospholipids have been noted to have a lower prevalence of IgE-associated disease in a dose-dependent manner (P<.05 and P<.05, respectively).⁴⁰ In another trial of 98 pregnant women randomized to fish oil supplementation or placebo from 20 weeks’ gestation to delivery found no difference in the frequency of AD but did note that infants in the exposure group had significantly less severe AD compared to controls (OR=0.09 [95% CI, 0.1-0.94]; P=.045).³⁹ A prospective birth cohort study of 2641 children evaluated dietary composition during the last 4 weeks of pregnancy and found that consumption of foods rich in n-6 LC-PUFAs (eg, margarine, vegetable oil) increased the risk for developing AD, while foods rich in n-3 LC-PUFAs (eg, fish) decreased the risk for developing AD in offspring at 2 years of age. All P values for margarine, vegetable oil, and fish were statistically significant on logistic regression at P<.05.⁴¹ A longitudinal analysis of follow-up data from a randomized controlled trial looking at maternal prenatal n-3 LC-PUFA intake and the development of allergic disease (including AD) found no differences in the development of disease at 1-, 3-, or 6-year follow-up.⁴² Despite several studies demonstrating a possible benefit of omega-3 fatty acid intake on the development of AD in offspring, the longitudinal analysis by Best et al⁴² reminds us that long-term follow-up is critical in establishing benefit of any intervention given the heterogeneous and progressive nature of the atopic march and AD. 

Specific Diets 

Several studies have evaluated the role of dietary patterns and their influence on atopic disease. Studies evaluating dietary patterns or supplement intake can be challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Further, analysis of any one food group does not account for the potential interplay between nutrients.⁴³ Studies should focus more on dietary patterns vs individual foods to assess true risk.^43,44 Given these limitations, study results on diet should be carefully scrutinized; however, there are still some positive findings that deserve further investigation. Chatzi et al⁴⁴ followed 460 children for 6.5 years and found a protective effect for the development of atopy in the offspring of women who had high adherence to the Mediterranean diet (OR 0.55 [95% CI, 0.31-0.97]). Another cohort study evaluating the effects of the Mediterranean diet and risk for AD in the first year of life in 2516 mother-child pairs from Spain and Greece found no statistically significant association with consumption of the Mediterranean diet and AD. The investigators also evaluated intake of fruits, nuts, vegetables, meats, processed meats, dairy products, and cereal and found no statistically significant protective benefit.⁴⁵ Another systematic review of more than 90 observational studies identified no significant relationship between prenatal dietary exposures of fruits, vegetables, nuts, fat, fatty acids, eggs, cereal, milk, alcohol, tea, or coffee and risk for allergic disease in offspring, including AD.¹⁹

A Chinese prospective cohort study evaluated the dietary protein patterns of 713 mother-child pairs and the incidence of infant AD at 6 months of age.⁴⁶ Dietary protein patterns were characterized as predominantly poultry, plant based, dairy and eggs, and red meat and fish. The investigators found a statistically significant reduced risk for AD in mothers who consumed plant-based or dairy and eggs protein patterns when compared to a poultry protein pattern with an adjusted OR of 0.572 (95% CI, 0.330-0.992) and 0.478 (95% CI, 0.274-0.837), respectively. This protective effect was not seen with the red meat and fish protein patterns.⁴⁶ Similar results were seen in a 2020 Canadian study that evaluated the effects of a Western (fats, meats, processed foods, and starchy vegetables), balanced (diverse sources of animal proteins [especially fish], fruits, vegetables, nuts, and seeds), or plant-based (dairy, legumes, vegetables, whole grains, and an aversion to meats) diet in more than 2000 mother-infant pairs from 24 to 28 weeks’ gestation to 1 year of age. The investigators found a lower OR of AD in mothers who followed a mostly plant-based diet compared to other dietary patterns (OR 0.65 [95% CI, 0.55-0.76]; P<.001).¹⁰ Another prospective Japanese study looking at healthy (high intake of green and yellow vegetables, seaweed, mushrooms, white vegetables, pulses, potatoes, fish, sea products, fruit, and shellfish, and low intake of confectioneries and soft drinks), Western (high intake of vegetable oil, salt-containing seasonings, beef, pork, processed meat, eggs, chicken, and white vegetables, and low intake of fruit, soft drinks, and confectioneries), or Japanese (high intake of rice, miso soup, sea products, and fish, and low intake of bread, confectioneries, and dairy products) dietary patterns in 763 mother-child pairs found no association between diet during pregnancy and development of AD in offspring at 16 to 24 months.⁴⁷ Unfortunately, a longitudinal data analysis has not been performed for this study.

Final Thoughts

Atopic dermatitis is a complex, progressive, and heterogeneous disease with both genetic and environmental influences. Studying the effects of diet on the development, progression, or severity of disease can be very difficult due to the heterogeneity of study designs, lack of long-term follow-up, and high potential for residual confounding. Studies evaluating dietary patterns or supplement intake can be equally challenging, as data often are derived from questionnaires with bias in response to families with higher socioeconomic status.⁹ Very few studies have looked specifically at maternal dietary composition and the development of AD alone (without inclusion of asthma or food allergy). Ultimately, the inconsistency of the data makes it difficult to draw conclusions and make formal recommendations for this vulnerable population. Additional evidence from well-powered trials with comparable methodology and objective outcome measures will be imperative to make formal recommendations. In addition, longitudinal follow-up will be essential to determine long-term benefit and influence on the atopic march.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.