[1735] Clonal Relationship of Plasma Cells to Lymphoid Component in Mantle Cell Lymphoma with Monotypic Plasma Cells

JT Malik, et al.. Multicenter Collaborative Study

Background: The differentiation of B-cells into plasma cells is a well-defined process that is regulated by transcriptional factors. Plasma cell precursors are mostly derived from the germinal center (GC) or marginal zone cells, and terminally differentiate into plasma cells at various peripheral sites. Primary follicle and mantle-zone B-cells are composed of naive, quiescent B-cells which rarely mature into plasma cells. These findings are reflected in B-cell lymphomas by the observations that while lymphomas arising from GC or post-GC B-cells often exhibit plasmacytic differentiation, this is a rare finding in lymphomas arising from pre-GC naive B-cells.
Design: Eight cases of mantle cell lymphoma (MCL) with monotypic plasma cell populations are identified from 6 medical centers. In each of these cases, the MCL cells and the plasma cells are evaluated by immunohistochemistry, fluorescence in situ hybridization (FISH), and Fluorescence immunophenotyping and Interphase Cytogenetics as a Tool for the Investigation of Neoplasms (FICTION) analysis.
Results: Three cases reveal typical morphologic and immunohistochemical features of MCL, but also contain small foci of plasma cells with identical monotypic immunoglobulin light chain expression. FICTION analysis demonstrates the characteristic t(11;14)(q13;q32) in the MCL cells and plasma cells in two of these three cases. Two cases are composed predominantly of clonal plasma cells with different immunoglobulin light chain expression. FICTION analysis demonstrates the t(11;14)(q13;q32) in the smaller population of MCL cells, but not in the larger population of plasma cells. One case is composed of MCL cells as well as smaller, monotypic plasma cell and non-MCL lymphoid components. FICTION analysis in this case, using light chain and CD138, demonstrates the t(11;14)(q13;q32) in the MCL cells but not in the plasma cells. FICTION analysis failed in two of the cases.
Conclusions: Our findings suggest that clonal monotypic plasma cells may accompany MCL cells. Immunohistochemical and molecular studies demonstrate that in two out of eight cases the MCL cells and plasma cells are derived from the same neoplastic B-cell clone. In four cases the plasma cells may represent a composite lymphoma of MCL and extramedullary plasmacytoma or plasmacytoma-like marginal zone lymphoma. FICTION analysis failed in two cases. Although MCL may rarely show plasmacytic differentiation, ancillary studies are needed to exclude a composite lymphoma.
Category: Pathobiology

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 219, Wednesday Morning


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