An autopsy case of B-cell lymphoma associated with macroglobulinemia (IgM-k).

While he was treated for macroglobulinemia showing symptoms, a 65-year-old man developed an enlargement of the left lateral cervical lymph node. Biopsy specimens of the cervical lymph node revealed large-cell non-Hodgkin's lymphoma. The lymphoma cells had rearrangement in the immunoglobulin heavy chain and kappa light chain genes. There was osteolysis involving right metatarsal bones. And, a tumor appeared on the upper hard palate in the terminal stage. Autopsy specimens showed infiltration of lymphoma cells into multiple organs. Production of monoclonal immunoglobulin M was detected only slightly and focally in the tumors. Plasmacytic differentiation as in Waldenström's macroglobulinemia was not seen in any organs except the tumor on the upper hard palate. From these findings, it is speculated that B-cell lymphoma might have developed in the course of macroglobulinemia.