[IgM kappa gastric plasmacytoma].

A case of gastric plasmacytoma in a 50-year old woman was reported. Immunofluorescent and immunoperoxidase studies were performed. Polyclonal antibodies reactive with immunoglobulin chains and a panel of 14 monoclonal antibodies reactive with B and T cells, and epithelial cells were used. These studies showed that the tumor cells produced IgM Kappa molecules whereas no monotypic immunoglobulin could be detected in the serum and urine. On the other hand the tumor cells had the immunologic phenotype of plasma cells. This helps diagnosis: some lymphomas with plasmocytic differentiation could also produce a monotypic immunoglobulin. Treatment using a combination of surgery, radio and polychimiotherapy was effective, leading to complete remission.