[A case of rheumatoid arthritis associated with multiple myeloma].

Previous reports have stressed the association between autoimmune disease and lympho-proliferative neoplasm. Here we report a patient in whom multiple myeloma developed about 30 years after the onset of rheumatoid arthritis. A 79 year-old woman with an about 30-year history of rheumatoid arthritis was admitted because of lumbago in December, 1993. Laboratory findings revealed M-proteinemia (IgA 2,380 mg/dl, IgG 728 mg/dl, IgM 51 mg/dl) and serum immunoelectrophoresis showed monoclonal IgA with lambda type light chain. Bone marrow aspirate contained 66.0% plasma cells. Serological tests of rheumatoid factor were positive. X-ray findings revealed radiolucent myelomatous foci in the skull and typical destructive changes of rheumatoid arthritis in multiple joint. From these findings, IgA lambda-type multiple myeloma with rheumatoid arthritis was diagnosed. Although the pathogenesis of the association between rheumatoid arthritis and multiple myeloma is unknown, prolonged antigenic stimulation manifested by rheumatoid arthritis is considered to be a possible pathogenetic factor in the development of multiple myeloma.