[Paraneoplastic pemphigus. Induction of autoantibodies against structural proteins in the skin]

Paraneoplastic pemphigus (PP) is a newly reported autoimmune disease, which is always associated with an underlying neoplasia. It is characterized by painful mucosal erosions and ulcerations, and by polymorphous skin lesions reminiscent of erythema multiforme, pemphigus vulgaris and lichen planus pemphigoides. These patients have autoantibodies that bind to a distinct complex of epidermal proteins, including desmoplakin I (250 kD), major bullous pemphigoid antigen (230 kD), desmoplakin II (210 kD) and a 190-kD and a 170-kD protein, neither of which has yet been further characterized. Histological findings include acantholysis, epidermal cell necrosis, vacuolar interface changes and, sometimes, lichenoid infiltrates of the upper dermis. Direct immunofluorescence shows an intercellular deposition of immunoreactants in the epidermis and granular deposits at the dermal-epidermal junction. Indirect immunofluorescence with rodent bladder as substrate shows an intercellular pattern. This method is the most convenient and cost-effective method of screening for PP, since antigens of both pemphigus vulgaris and pemphigus foliaceus are not expressed in this tissue.