Clinical, Immunophenotypic, and Genetic Characterization of Small Lymphocyte–Like Plasma Cell Myeloma

Abstract

We reviewed bone marrow studies from 351 multiple myeloma (MM) cases, selecting 12 cases (3.4%) with predominantly small lymphocyte–like morphologic features resembling B-cell lymphoma, and correlated their genetic and clinical features. All exhibited a diffuse interstitial pattern of marrow involvement. Small lymphocyte–like plasma cells were all CD45− with bright CD38 and CD138 expression and CD20 expression in 5 cases. No case had an increase in bone marrow B lymphocytes by flow cytometry. Of 12 cases, 9 were classified as the CD-2 molecular class by gene expression profiling (GEP). The 29 CD-2 class cases with (n = 9) and without (n = 20) small lymphocyte–like features could not be discerned from one another using global GEP. Event-free, but not overall, survival was significantly better in cases with small lymphocyte–like features among those sharing the CD-2 subtype. Small lymphocyte–like MM is a rare, morphologically challenging variant distinguished from B-cell lymphoma by lack of CD45 and presence of CD138 and the clinical presentation of MM. Most cases share a common GEP signature dominated by hyperexpression of cyclin D1 or cyclin D3 genes, with increased expression of the B-cell genes CD20 and VPREB3.

Diagnostic and Clinical Considerations in Concomitant Bone Marrow Involvement by Plasma Cell Myeloma and Chronic Lymphocytic Leukemia/Monoclonal B-Cell Lymphocytosis: A Series of 15 Cases and Review of Literature

“…Conversely, the plasma cells may express CD20 in about 10% of cases 67 and may have a lymphocyte-like ''small cell'' morphology in about 3% to 4% of cases. 68 When small plasma cells express CD20 and CD45, along with cyclin D1 (which is seen in 75% of ''small cell'' myelomas), distinction from mantle cell lymphoma is facilitated by demonstrating the CD138 þ and CD5 -phenotype of the plasma cells. 68 Are the CD5 þ abnormal B cells and monotypic plasma cells occurring concomitantly in the marrow biologically related and what are the clinical implications of this rare event?…”

“…68 When small plasma cells express CD20 and CD45, along with cyclin D1 (which is seen in 75% of ''small cell'' myelomas), distinction from mantle cell lymphoma is facilitated by demonstrating the CD138 þ and CD5 -phenotype of the plasma cells. 68 Are the CD5 þ abnormal B cells and monotypic plasma cells occurring concomitantly in the marrow biologically related and what are the clinical implications of this rare event? It is generally accepted that normal plasma cells are terminally differentiated, specialized cells arising from B cells, 69 and it is theoretically possible that the monotypic plasma cells are further differentiated or transformed CLL cells.…”

Small-lymphoid cells and myeloid antigen expression in a patient with IgG myeloma: A case report

“…2G and H). The abnormal cells were negative for CD117, CD10, CD20, CD22, CD34 and CD13 expression (data not presented 3,518 µg/l; IgG, 70.7 g/l; and bone marrow, 18.5% plasma cells. The patient was treated with the DECP regimen, which consisted of 20 mg dexamethasone, 100 mg etoposide, 0.6 g cyclophosphamide and 30 mg cisplatinum for 4 days.…”

“…MM is often associated with extensive skeletal destruction, anemia, hypercalcemia, infections and renal failure (2). However, certain cases presenting with atypical features may be challenging for hematopathologists to diagnose (3). The current study describes a case of immunoglobulin G (IgG) myeloma presenting with small lymphoid cells.…”

New developments in the pathology of malignant lymphoma: a review of the literature published from October 2009 to January 2010

“…Etienne et al [58] investigated 16 patients with myelofibrosis who developed a lymphoma. They report that a variety of types occur but that this second malignancy does not result in a poorer prognosis for these patients.…”