Histologic Features of Paraneoplastic Pemphigus

Background.—We describe the histopathologic features of paraneoplastic pemphigus, a recently described autoimmune mucocutaneous disease associated with neoplasia. Complete evaluation for paraneoplastic pemphigus requires identification of the characteristic mucocutaneous eruption, tissue specimens for routine histologic and direct immunofluorescence evaluation, and identification of circulating autoantibodies with a unique specificity. Immunoprecipitation from keratinocytes reveals a characteristic complex of four proteins with the circulating antibodies. Various neoplasms have been identified in patients with paraneoplastic pemphigus. Observations.—We reviewed 16 skin and oral mucous membrane biopsy specimens from six patients with paraneoplastic pemphigus confirmed by fulfillment of all criteria. Major features include epidermal acantholysis, suprabasal cleft formation, dyskeratotic keratinocytes, vacuolar change of the basilar epidermis, and epidermal exocytosis of inflammatory cells. Seven (44%) of 16 specimens displayed a unique combination of suprabasal acantholysis and dyskeratotic keratinocytes throughout the epidermis. These histologic findings correspond to those of the characteristic clinical lesions that are described as having features of pemphigus and erythema multiforme. Conclusions.—Paraneoplastic pemphigus represents a unique clinical, histologic, and immunologic disease characterized by autoantibody production to desmoplakin I and desmoplakin II, bullous pemphigoid antigen, and, possibly, other antigens in the desmosomal complex. Recognition of the histologic features should prompt immunopathologic confirmation and evaluation for an occult neoplasm.