Introduction
Dermatitis herpetiformis is a rare skin disorder associated with coeliac disease. The name herpetiformis refers to the fact that the rash often resembles the rash caused by herpes zoster (shingles and chickenpox).
Aetiology
- Adulthood (20-40)
- Coeliac’s disease (transglutaminase)
- M:F 2:1
Pathophysiology
- Deposition of IgA in papillary dermis causing an immunological cascade
- Is an immunologic response to chronic stimulation of the gut mucosa. IgA react to gluten-tissue transglutaminase (t-TG) in the gut, and epidermal transglutaminase (e-TG).
- Genetic predisposition with HLA expression (10% have affected relative)
Signs & Symptoms
- ‘Suicidally itchy’ blisters and papules. Intensely pruritic
- Often few blisters as most are scratched and therefore appear as papules
- Intermittent cutaneous lesions mainly affecting the buttocks, knees and elbows
- Rraely any bowel symptoms of coeliac’s disease
Management
Gluten free diet for life to control symptoms and reduce risk of small bowel lymphoma.
Other agents can help to get the rash under control, but will typically not have any benefit for the underlying bowel disease. These may include:
- Dapsone (antibacterial) – 50mg once daily
- Sulphapyridine (sulphonamide ABx)
- Betamethasone 0.05% – a potent topical steroid
References
- British Association of Dermatologists: Dermatology, a handbook for medical students & junior doctors
- bad.org.uk
- dermnetnz.org