A 73-year-old man was admitted to our hospital in July 1996 because of lymphoctyosis and
lumbago. Physical examination revealed
hepatomegaly and
anemia. Hematologic examination showed a
hemoglobin concentration of 9.6 g/dl and a leukocyte count of 32,700/microliter with 74% abnormal mononuclear cells. In Wright-Giemsa stained blood films, these cells had short villi arising from 1 or 2 poles. Immunophenotyping of peripheral mononuclear cells showed moderate to strong expression of CD10, CD24, CD38, and sIg lambda, but not of CD19, CD20, or CD25. Southern blot analysis of the peripheral mononuclear cells demonstrated rearranged monoclonal bands in the C lambda. Urine immunoelectrophoresis detected a monoclonal band identifiable as lambda-type
Bence Jones protein. In addition, bone X-ray studies disclosed multiple osteolytic lesions. A diagnosis of
plasma cell leukemia was made, and the patient was placed on
chemotherapy consisting of
cyclophosphamide and
prednisolone. No notable improvement in laboratory findings was seen but the patient experienced an indolent
clinical course. He died of
pneumonia in January 1998. The morphological and clinical findings were unusual for a case of
plasma cell leukemia. This case study suggested that signs of
lymphocytosis require immunophenotypic and electron microscopic studies for the differential diagnosis of
plasma cell leukemia.