[Two-peak monoclonal protein (IgA kappa and IgG kappa) in non-Hodgkin lymphoma]

A 72-year-old man was admitted because of general weakness. On physical examination, marked splenomegaly was found. Blood tests revealed anemia, thrombocytopenia and two-peak hypergammaglobulinemia composed of kappa type IgG and IgA monoclonal proteins. Peripheral blood and bone marrow (BM) contained abnormal lymphocytes including plasmacytoid lymphocytes and/or plasma cells. Pathological examination of the biopsied BM showed non-Hodgkin lymphoma consistent with the lymphoplasmacytoid type. Immunohistochemical staining revealed two different populations of cells, one with IgG and the other with IgA; no cell stained both and no solitary cluster of either IgG or IgA positive cell was seen. The surface phenotype of the lymphoma cells was CD19+, CD20+, HLADR+. Double immunofluorescence staining of the BM smear showed IgG or IgA positive plasma cells, whereas small lymphocytes were negative for IgG and IgA. Analysis of immunoglobulin genes in the BM cells showed 2 rearranged bands in each of heavy chain genes and kappa light chain genes. The patient was treated with modified MVCP therapy and the two monoclonal proteins decreased in parallel with the improvement of splenomegaly. These findings strongly suggest that the two-peak monoclonal protein was produced by monoclonal lymphoma cells. The patients has been disease-free without any therapy since August, 1995.