Paraneoplastic pemphigus

A rare disease: Paraneoplastic pemphigus is an rare autoimmune bullous skin recently recognized. About 50 cases have been reported since its first des cription in 1990. Clinical manifestations: Clinical signs are polymorphous resembling the cut aneomucosal manifestations of pemphigus vulgar (skin and mucose erosions, f ragile interdermal bullae), pemphigoid (urticaria, distended subepidermal b ullae), and polymorphous erythema (plaque lesions). Mucosal erosions predom inate however. Associated cancers: Most cancers associated with paraneoplastic pemphigus a re hematologic diseases (non-Hodgkin's lymphomas, chronic lymphoid leukemia ). Severe prognosis: No standard treatment has been defined. General corticost eroids and treatment of the causal disease are indicated. The clinical cour se of paraneoplastic pemphigus does not always follow the course of the ass ociated neoplasm. Positive diagnosis: Pathology criteria (keratinocyte necrosis, suprabasal k eratinocyte vacuolization, intraepidermal acantholysis) and immunohistologi cal findings (antibody and complement deposits at the dermo-epidermal junct ion and within the keratinocytes on different epithelial substrates) are in sufficient for positive diagnosis. Autoantibodies must be identified by imm unoprecipitation or immunoblotting to identify the target antigen complex: plakin components (desmoplakin I and II, periplakin, envoplakin), the major pemphigoid antigen, desmoglein 3, and certain yet unidentified antigens wi th a molecular weight of 170 kD. Pathogenesis: Paraneoplastic pemphigus appears as a model autoimmune parane oplastic disease. Its origin remains elusive. It has been hypothesized that tumor-induced inhibition of tolerance to certain antigens implicated in th e keratinocyte junctional systems could be involved.