Bullous Pemphigoid

Subepidermal blister caused by an autoimmune reaction

Epidemiology

• Most common autoimmune blistering disease

• Typically affects the elderly (≥60 years)

• Slight female predominance

• Increased incidence with:
• Neurological diseases (stroke, Parkinson’s disease, dementia)
• Physical triggers (trauma, radiation, burns)

• Drug-induced BP reported with DPP-4 inhibitors, diuretics, antibiotics

Aetiology

Autoimmune Targets

• BP180 (type XVII collagen) – major pathogenic antigen

• BP230 – intracellular plaque protein

Pathophysiology

• Autoantibody binding → complement activation (C3)

• Recruitment of eosinophils, neutrophils

• Release of proteolytic enzymes

• Subepidermal blister formation — dermo-epidermal junction

Clinical presentation

Prodromal (Non-bullous) Phase

• Severe pruritus

• Urticarial, eczematous, or erythematous plaques

• May last weeks to months

Bullous Phase

• Tense, fluid-filled bullae

• Erythematous or normal surrounding skin

• Bullae do not rupture easily

• Nikolsky sign negative

Distribution

• Trunk

• Flexural surfaces of limbs

• Abdomen

• Axillae, groin

Mucosal Involvement

• Uncommon (<20%)

• Much milder than pemphigus vulgaris

Investigations

Immunofluorescence (Gold Standard)

Histopathology

• Subepidermal blister

• Eosinophil-rich inflammatory infiltrate in dermis

Management

First-line Therapy

• High-potency topical corticosteroids (e.g., clobetasol propionate)
– preferred in localized and even generalized disease

Systemic Therapy (if extensive)

Supportive Care

• Wound care

• Treat secondary infection

• Manage comorbidities