dermatologic disorders
Pemphigus Vulgaris
Introduction
Pemphigus vulgaris is an uncommon, potentially fatal, autoimmune disorder characterized by intraepidermal blisters and extensive erosions on apparently healthy skin and mucous membranes. Diagnosis is by skin biopsy with direct and indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA) testing. Treatment is with corticosteroids and sometimes other immunosuppressive therapies. Bullae are elevated, fluid-filled blisters ≥ 10 mm in diameter. Pemphigus vulgaris usually occurs in middle-aged patients, affecting men and women in equal numbers. Rarely, cases have been reported in children. One variant, paraneoplastic pemphigus, can occur in patients who have malignant or benign tumors, most commonly Non-Hodgkin Lymphomas . Pemphigus vulgaris is characterized by IgG autoantibodies directed against the calcium-dependent cadherins desmoglein 3 and sometimes desmoglein 1 ( General reference ). Paraneoplastic pemphigus has autoantibodies directed against these desmoglein antigens as well as others (eg, envoplakin, peiplakin, desmoplakin 1 and 2, BP-Ag 1). These transmembrane glycoproteins affect cell-cell adhesion and signaling between epidermal cells. Acantholysis (loss of intercellular adhesion with consequent epidermal blister formation) results from either direct inhibition of desmoglein function by autoantibody binding or from autoantibody-induced cell signaling that results in down-regulation of cell-cell adhesion. The autoantibodies are present in both serum and skin during active disease. Any area of stratified squamous epithelium may be affected, including mucosal surfaces (see figure 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. Pemphigus (vulgaris, foliaceus, or both) may coexist with certain central nervous system (CNS) disorders, especially dementia, epilepsy, and Parkinson disease. Desmoglein 1 is present in CNS neurons (and in all epithelial cells), and an immunologic cross-reaction between epithelial and CNS isoforms has been suggested. 