Concomitant Waldenstrom macroglobulinemia and IgA plasmablastic myeloma in a patient with untreated IgM paraproteinemia: sequential development of biclonal B-cell neoplasms over a 10-year period in a single individual.

Waldenstrom macroglobulinemia and plasma cell myeloma are both mature B-cell neoplasms primarily involving bone marrow and frequently demonstrating paraproteinemia. Plasma cell myeloma has been described in association with other indolent B-cell lymphomas, particularly chronic lymphocytic leukemia, but concomitant Waldenstrom macroglobulinemia and plasma cell myeloma has not been previously described. We report the first case of sequential development of Waldenstrom macroglobulinemia and plasma cell myeloma over a 10-year period in a 73-year-old man with untreated IgM paraproteinemia. The bone marrow biopsy demonstrated dual populations of lymphoid cells: small mature lymphocytes and immature plasma cells. Although both Waldenstrom macroglobulinemia and plasma cell myeloma were restricted to κ light chain, plasma cell myeloma expressed IgA, whereas the plasmacytic component in Waldenstrom macroglobulinemia produced IgM. The biclonal nature of these 2 B-cell neoplasms was further supported by immunofixation electrophoresis and cytogenetic studies. Although the clinical outcome of plasma cell myeloma when concomitant with other indolent B-cell neoplasms is unfavorable, our patient seemed to respond to high-dose bortezomib plus lenalidomide.