Cytogenetic Study and Analysis of Protein Expression in Plasma Cell Myeloma with t(11;14)(q13;q32): Absence of BCL6 and SOX11, and Infrequent Expression of CD20 and PAX5.

The t(11;14)(q13;q32) translocation is the most common chromosomal translocation in plasma cell myeloma (PCM), but the cytogenetic and immunophenotypic features of PCM with t(11;14)(q13;q32) remain to be fully elucidated. To address the issue, we retrospectively analyzed 21 newly diagnosed PCM patients with the t(11;14)(q13;q32) translocation in our institute. CD20 is a B-cell-specific transmembrane protein that is the topic of much focus as a potential target in immunotherapy. We observed a low incidence of CD20 expression (2 of 21 patients, 11%), although the expression of CD20 was previously reported to be associated with t(11;14)(q13;q32). PAX5 is an essential transcriptional factor involved in B-cell development and commitment, and is down-regulated upon plasma cell differentiation. We observed one patient (6%) with expression of PAX5. The expression of CD19, CD56, and CD138 was detected in one (0.7%), nine (60%), and 13 patients (87%), respectively. Cyclin D1, CD38, and BCL2 were detected in all patients; on the other hand, neither BCL6 nor SOX11 was detected in any of the evaluated patients. Abnormalities of chromosome 13 were detected in six patients (38%), but deletion of TP53 was not observed in any of the evaluated patients. Our results suggest the absence of BCL6 and SOX11 expression, and infrequent expression of CD20, PAX5, and CD56 in PCM with t(11;14)(q13;q32), in contrast to the findings of earlier reports.