Japanese Journal of Clinical Oncology 33:232-237 (2003)
© 2003 Foundation for Promotion of Cancer Research
A Case of Primary Plasma Cell Leukemia with Hairy-cell Morphology and Lambda-type BenceJones Protein. Immunohistochemical and Molecular Analysis
1 Division of Pathology and Laboratory Medicine, Iwata City Hospital, Iwata, Shizuoka, Departments of 2 Hematology and 3 Pathology, Seirei Hamamatsu Hospital, Hamamatsu, Shizuoka, 4 Hematology Division, National Cancer Center Hospital, Tokyo and 5 First Department of Pathology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
A case of primary plasma cell leukemia with hairy-cell morphology and lambda-type BenceJones protein is reported. Most of the atypical cells in the peripheral blood of this case were small lymphoid cells or lymphoplasmacytoid lymphocytes with numerous cytoplasmic hairy projections. Plasmablastic cells and tadpole-like cells were also present in the bone marrow. Immunohistochemically, these atypical cells expressed the cytoplasmic lambda light chain and surface CD38 proteins but were negative for B-cell markers such as CD19, CD20 and CD79a. VLA-5 (CD49e), which is supposed to be expressed in mature populations of plasma cells, was negative. A sequence analysis of the variable region gene in the light-chain (VL) and heavy-chain (VH) loci of immunoglobulin demonstrated significant somatic hypermutation and intraclonal nucleic acid sequence variations. To our knowledge, the intraclonal diversity of these loci has been previously reported in some cases of monoclonal gammopathy of undetermined significance (MGUS), but never in a case of multiple myeloma. The immunohistochemical and molecular characteristics of this case allowed us to delineate the origin of the leukemic cells with hairy cell-morphology as germinal center B-cells, which would be at a more immature stage than the presumable origin of multiple myeloma.
+ For reprints and all correspondence: Haruhiko Sugimura, First Department of Pathology, Hamamatsu University School of Medicine, 1201 Handayama, Hamamatsu 431-3192, Japan. E-mail: hsugimur{at}hama-med.ac.jp