Abstract
A 81-year-old man was admitted to our hospital because of fever and body weight loss. He looked pale, and physical examination revealed hepatosplenomegaly and petechiae on the lower extremities. The white-cell count was 113,000 with 90 per cent small lymphocytes, and a bone marrow aspiration revealed hypercellularity with 80 per cent lymphocytes. X-ray examination showed diffuse osteolytic lesions throughout the skeletal system. Serum IgM was 1,656 mg/dl, and serum immunoelectrophoresis disclosed a marked monoclonal increase in IgM-κ. Immunofluorescence study showed that most lymphocytes carried the monoclonal IgM-κ on their surface, and a limited number of lymphocytes were also positive for intracytoplasmic IgM-κ. Using antiidiotypic antibody prepared against serum IgM, the idiotype of serum monoclonal IgM was proved to be identical with that of cell surface and intracytoplasmic IgM of the circulating lymphocytes. A marrow biopsy of the iliac bone disclosed nodular proliferation of the lymphocytes, but positive PAP staining for intracytoplasmic IgM-κ was restricted to a small number of plasma cells around the nodules.
This case was not only a rare one of leukemic macroglobulinemia associated with diffuse osteolytic lesions, but also interesting in point of the maturation and differentiation of B lymphocytes.
