dermatologic disorders
Bullous Pemphigoid
Introduction
Bullous pemphigoid is a chronic autoimmune skin disorder resulting in generalized, pruritic, bullous lesions in older patients. Mucous membrane involvement is rare. Diagnosis is by skin biopsy and immunofluorescence testing of skin and serum. Topical and systemic corticosteroids are used initially. Most patients require long-term maintenance therapy, for which a variety of immunosuppressants can be used. Bullae are elevated, fluid-filled blisters ≥ 10 mm in diameter. Bullous pemphigoid occurs more often in patients > age 60 but can occur in children. IgG autoantibodies bind to certain hemidesmosomal antigens (BPAg1 [BP230], BPAg2 [BP180]), resulting in the activation of complement to form a subepidermal blister (see figure Skin cleavage levels in pemphigus and bullous pemphigoid ). Pemphigus foliaceus blisters form in the superficial layers of the epidermis. Pemphigus vulgaris blisters can form at any epidermal level but typically form in the lower aspects of the epidermis. Bullous pemphigoid blisters form subepidermally (lamina lucida of the basement membrane zone). In this figure, the basement membrane zone is disproportionately enlarged to display its layers. 