Dermatitis Herpetiformis

Dermatitis herpetiformis is an uncommon disease manifested by pruritic papules, vesicles, and papulovesicles mainly on the elbows, knees, buttocks, posterior neck, and scalp. It appears to have its highest prevalence in Scandinavia and is associated with HLA antigens -B8, -DR3, and -DQ2. The diagnosis is made by light microscopy, which demonstrates neutrophils at the dermal papillary tips. Direct immunofluorescence studies show granular deposits of IgA along the dermal papillae.

Circulating antiendomysium antibodies and antibodies to tissue transglutaminase are present in 70% of cases. Patients have gluten-sensitive enteropathy, but for the great majority it is subclinical. However, ingestion of gluten plays a role in the exacerbation of skin lesions, and strict long-term avoidance of dietary gluten has been shown to decrease the dose of dapsone (usually 100–200 mg/d) required to control the disease and may even eliminate the need for drug treatment. Although adherence to a gluten-free diet is difficult, the availability of many gluten-free foods makes this easier to accomplish. Patients with dermatitis herpetiformis are at increased risk for development of gastrointestinal lymphoma, and this risk is reduced by a gluten-free diet.