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

• 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

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Not to be confused with Bullous Pemphigoid. Pemphigus is also often referred to as Pemphigus Vulgaris although technically this only refers to one particular type of pemphigus.

Aetiology

•  Middle aged (40-60yrs)
•  High prevalence in Jewish regions
•  Lifelong condition

Pathophysiology

• Autoimmune, epidermal blistering due to IgG  autoantibodies for keratinocyte surfaces (desmoglein)
• Often mucosal involvement (>90%)
• Potentially life threatening (rare) if it is paraneoplastic

Signs & Symptoms

• <50% present with oral lesions
• Thin roofed & flaccid blisters (superficial) that are easily ruptured
• Uusally No Prodromal Symptoms
• Affected skin painful put not pruritic
• Nikolsky Sign – slight rubbing exfoliates the outermost layer of skin (not present in pemphigoid)

Management

• Oral steroids
• Plasmapharesis in severe cases

References:

• British Association of Dermatologists: Dermatology, a handbook for medical students & junior doctors – bad.org.uk
• dermnetnz.org

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Aetiology

• Elderly (>65yrs)
• Vaccinations (in children with  condition affecting face, palms and soles)
• NSAIDs, furosemide, antibiotics
• UV radiation / x-rays

Pathophysiology

• Autoimmune, subepidermal blistering due to IgG  autoantibodies for the basement membrane proteins BP1 and BP2.
• IgG bind to basement membrane and activate inflammatory cascade.

Signs & Symptoms

• Present acutely or insidiously
• Often a pruritic prodromal rash & region
• Thick, tense blisters  & erosions appear typically in flexural regions of limb and trunk
• Self limiting @ 2 yrs
• Usually heal without scarring (unless cicatricial pemphigoid involving the mucous membrane)

Management

• Topical if localised, systemic if severe.

• Corticosteroids (prednisolone)

• Immunosuppressants (azathioprine/methotrexate)

• British Association of Dermatologists: Dermatology, a handbook for medical students & junior doctors
• bad.org.uk
• dermnetnz.org

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