Dermatitis herpetiformis is a chronic, intensely pruritic, blistering disorder associated with gluten-sensitive enteropathy (celiac disease). It presents with grouped vesicles and excoriated papules on extensor surfaces, buttocks, and scalp. Immunopathology shows granular IgA deposition in dermal papillae. Dapsone provides rapid symptom relief, but strict lifelong gluten-free diet is the mainstay to reduce enteropathy, lymphoma risk, and medication dependence.
Epidemiology
- More common in individuals of Northern European descent; male predominance in DH (contrast celiac’s female predominance).
- Onset typically 20–50 years; pediatric cases occur.
Pathophysiology
- Gluten exposure leads to IgA antibodies against epidermal transglutaminase (TG3) that deposit in skin, causing neutrophil-rich microabscesses and subepidermal vesiculation.
- Intestinal mucosa often shows villous atrophy; some patients are asymptomatic for GI symptoms.
Clinical Features
- Symmetrical intensely pruritic papulovesicles and excoriations on elbows, knees, buttocks, lower back, and scalp; face can be involved.
- Vesicles are fragile and often absent due to scratching; postinflammatory dyspigmentation and lichenification common.
- Associated conditions: other autoimmune diseases (thyroid disease, type 1 diabetes), nutritional deficiencies (iron, folate).
Differential Diagnosis
- Scabies (burrows, interdigital involvement), papular urticaria, bullous pemphigoid (elderly, tense bullae), linear IgA disease, eczema with excoriations.
Diagnostic Workup
- Perilesional skin for DIF: granular IgA in dermal papillae (gold standard).
- Serology: anti–tissue transglutaminase (tTG-IgA), anti-endomysial antibodies, anti-TG3; check total IgA (IgA deficiency can cause false negatives).
- Small bowel biopsy for celiac disease as indicated; screen for nutritional deficiencies and thyroid disease.
Management
- Pharmacologic
- Dapsone: rapid control of pruritus within days; start low (25–50 mg/day) and titrate; monitor for hemolysis/methemoglobinemia; obtain baseline G6PD, CBC, retic count, LFTs; educate on symptoms of hemolysis.
- Alternatives if dapsone intolerant: sulfapyridine/sulfamethoxypyridazine; topical potent steroids for localized itch as adjuncts.
- Dietary
- Strict lifelong gluten-free diet (GFD): reduces skin and gut activity, allows dapsone taper and eventual discontinuation in many; requires dietician support.
- Monitor adherence with serologies and symptom tracking; address nutritional deficiencies (iron, folate, B12, vitamin D).
- Monitoring and Counseling
- Regular labs while on dapsone (CBC, methemoglobin as indicated).
- Screen and manage associated autoimmune diseases.
- Educate that skin improvement with GFD lags by months; temporary need for dapsone during this period is typical.
Prognosis
- Excellent with adherence to GFD; risk of enteropathy-associated T-cell lymphoma reduced by strict diet.
- Relapses occur with gluten exposure.
References (recent guidelines and reviews)
- International guidelines on DH and celiac disease management, 2021–2024.
- Studies on TG3 antibodies and DH pathogenesis, 2022–2024.
- Safety and monitoring recommendations for dapsone therapy, 2022–2024.