[Two cases of rheumatoid arthritis associated with IgA -type multiple myeloma].

We report here two Japanese cases of rheumatoid arthritis (RA) associated with IgA [symbol: see text]-type multiple myeloma (MM). Case 1. The patient was a 68-year-old man with eight-years history of RA. The M-proteinemia (IgA 2838 mg/dl) in laboratory findings suggested a complication of MM which had been noticed since four years ago. On May 1997, he was referred and admitted to our hospital because of cough, right chest pain and dyspnea. Serum immunoelectrophoresis showed monoclonal IgA[symbol: see text]-type light chain. Bone marrow aspirate contained 6.5% atypical plasma cells. The X-ray findings revealed radiolucent myelomatous foci in the skull. From these findings, IgA[symbol: see text]-type MM was diagnosed. His condition was recovered by administration of antibiotics for bacterial pleuritis. Case 2. The patient was a 75-year-old woman with twelve-years history of RA. The laboratory findings of M-proteinemia (IgA 1215 mg/dl) with the decrease of other serum immunoglobulin level (IgG 611 mg/dl, IgM 60 mg/dl) and monoclonal IgA[symbol: see text]-type light chain in serum immunoelectrophoresis suggested MM four years ago. Bone marrow aspirate contained 5% plasma cells. From these findings, IgA[symbol: see text]-type MM was diagnosed. In the review of reported Japanese cases of RA associated with MM, it might be characteristic that IgA type MM was found more frequently in RA patients than other immunoglobulin types.