A 35-year-old man presented with a generalized bullous eruption and oral ulceration. He had been diagnosed as having systemic lupus erythematosus and pelvic Castleman disease (hyaline-vascular type) in the past. Histologic, direct and indirect immunofluorescence and immunoprecipitation studies confirmed a diagnosis of paraneoplastic pemphigus (PNP). Initially several medical treatments were tried unsuccessfully. The pelvic tumor was surgically removed and the mucocutaneous lesions slowly regressed. Four years after presentation, he developed polymyositis which was completely controlled with short courses of corticosteroids. There was no evidence of relapse of PNP or lupus erythematosus at that time. At the 6-year follow-up he showed no clinical evidence of PNP, lupus erythematosus or polymyositis without requiring immunosuppressive therapy. This case emphasizes the fact that patients with benign-neoplasm-associated PNP may undergo complete remission of the autoimmune disease upon complete excision of the tumor. This case also stresses the possible association of PNP with other autoimmune diseases such as lupus erythematosus and polymyositis.