6-24: 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 (eFigure 6–48). It appears to have its highest prevalence in Northern Europe and is associated with HLA antigens -B8, -DR3, and -DQ2. The histopathology is distinctive. Circulating antibodies to tissue transglutaminase are present in 90% of cases. NSAIDs may cause flares. Patients have gluten-sensitive enteropathy, but it is subclinical in the great majority. However, ingestion of gluten is the cause of the disease, and strict long-term avoidance of dietary gluten has been shown to decrease the dose of dapsone (initial treatment dose is 100–200 mg orally daily) required to control the disease and may even eliminate the need for treatment. Patients with dermatitis herpetiformis are at increased risk for development of gastrointestinal lymphoma, and this risk is reduced by a gluten-free diet.