FFinalistSouthampton · 2027
Dermatology
AKT · Dermatology/Inflammatory & papulosquamouslow yield

Dermatitis herpetiformis

IgA-mediated cutaneous manifestation of coeliac disease

Overview

An intensely itchy, chronic, blistering eruption that is the cutaneous expression of COELIAC disease (gluten-sensitive enteropathy), mediated by IgA antibodies. Symmetrical grouped vesicles/papules on the extensor surfaces; the key links are the gluten enteropathy and the response to a gluten-free diet (and dapsone).

Recognise

  • Intensely itchy/burning, symmetrical, grouped vesicles and excoriated papules on EXTENSOR surfaces — elbows, knees, buttocks, scalp
  • Often only excoriations are seen (the vesicles are scratched away); associated with coeliac disease (most have enteropathy, often asymptomatic)
  • Associated autoimmune conditions (thyroid disease, type 1 diabetes)

Red flags

  • Underlying coeliac disease → malabsorption, and a long-term small-bowel lymphoma risk if untreated

Differentials & how to tell them apart

Scabiesburrows in finger webs, itchy contacts — DH is symmetrical extensor with granular IgA on DIF
Atopic eczemaflexural, atopy history, no granular IgA
Bullous pemphigoidtense bullae in the elderly, LINEAR IgG/C3 (not granular IgA)
Insect bites/papular urticariano coeliac association or IgA deposits

Clinical image

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Dermatitis herpetiformis — clinical imagesDermNet

Investigations

Skin biopsy with DIRECT IMMUNOFLUORESCENCE showing granular IgA deposits in the dermal papillae (diagnostic); coeliac serology (anti-tissue transglutaminase/endomysial IgA) + duodenal biopsy; screen for associated autoimmune disease.

Management

Lifelong gluten-free diet + dapsone for rapid symptom control

  1. 1Confirm with skin biopsy + direct immunofluorescence (granular IgA) and coeliac work-up. Start a lifelong GLUTEN-FREE DIET (treats the cause) and dapsone for rapid relief of the itch/rash.Gate: Check G6PD status before dapsone (it causes haemolysis, severe in G6PD deficiency); and recognise that dermatitis herpetiformis IS coeliac disease in the skin — the gluten-free diet, not just dapsone, is the disease-modifying treatment
  2. 2Dietitian input; monitor coeliac serology and adherence; screen for and manage associated autoimmune disease; the diet allows dapsone to be tapered over time.
Gluten-free diet — the definitive long-term treatment (clears skin and gut over months, reduces lymphoma risk)
Dapsone — rapid control of the itch/rash while the diet takes effect (check G6PD first — haemolysis risk)

Key points

Itchy symmetrical extensor vesicles + coeliac = dermatitis herpetiformis; DIF shows granular IgA. Gluten-free diet is curative; dapsone gives fast relief (check G6PD first).

Monitor & prognosis

Itch/rash control, coeliac serology, dietary adherence, dapsone (FBC/haemolysis).

Excellent on a gluten-free diet; relapses with gluten re-exposure.

Source: NICE CKS Coeliac disease; DermNet