Leukemia in a Patient With Multiple Myeloma

Abstract

Laboratory Evaluation Complete blood count at the time of admission revealed a normal hemoglobin, platelet count, and white blood cell count. However, the differential white blood cell count revealed 59% lymphoplasmacytic cells. Peripheral blood smear examination [I1] revealed a predominance of lymphocytes with plasmacytoid differentiation. Flow cytometric analysis of these cells revealed expression of CD38 and CD138 with cytoplasmic lambda light chain restriction [F1]. Neither CD20 nor other B lymphocyte antigens were expressed. Molecular cytogenetic studies by fluorescence in situ hybridization (FISH) using DNA probes for loci at 11q23 (ATM), 13q14.3 (RB1), 13q34, and 17p13.1 (p53) revealed duplication/trisomy for the 11q23/ATM locus and concomitant deletion of targeted loci on chromosome 13 (13q14.3/RB1 and 13q34) [I2]. Fluorescence in situ hypridization analyses using probes for chromosomes 6, 9, and 12 were within normal limits without clonal abnormalities. No conventional cytogenetic studies were performed. Urine and serum immunoelectrophoresis, skeletal survey, and bone marrow biopsy were performed. The 24 hour total urine protein was 3,689 mg/dL. Serum and urine electrophoresis and immunofixation studies revealed monoclonal lambda light chain with free lambda light chains in urine. Most of the M component was in the urine and was comprised of lambda light chain which constituted 62.5% of the total urine protein. Imaging studies revealed osteolytic lesions in the femur and humerus. The bone marrow biopsy was hypercellular with greater than 95% lymphoplasmacytic cells [I3], most of which had small nucleoli. Tumor cells expressed CD38 [I4] and cytoplasmic lambda light chain on immunoperoxidase staining. Electron microscopy of tumor cells from the peripheral blood revealed irregular shaped nuclei, a high N:C ratio, scattered mitochondria, and numerous parallel arrays of rough endoplasmic reticulum [I5]. The cell surface revealed thin, short filopodia. The laboratory and clinical findings were consistent with the diagnosis of plasma cell leukemia.