Paraneoplastic pemphigus without antidesmoglein 3 or antidesmoglein 1 autoantibodies

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous blistering di sease characterized by IgG autoantibodies that bind to various epithelia an d immunoprecipitate a complex of 250, 230, 210, 190 and 170 kDa proteins. A recent study has suggested that PNP patients have antidesmoglein (Dsg) 3 a utoantibody and that the antibody plays a pathogenic role in PNP. We report a 72-year-old woman with PNP associated with thymoma and adenocarcinoma of the lung. Diagnosis of PNP was made by the characteristic clinical, histol ogical and immunopathological findings, as well as immunoprecipitation of c haracteristic 230, 210 and 190 kDa proteins. Using enzyme-linked immunosorb ent assay with baculovirus-expressed recombinant: proteins, the patient's s erum was negative against both Dsg 3 and Dsg 1. This finding is unusual, an d it suggests that the target antigen, which is involved in acantholysis, m ay be other than Dsg 3 in this case.