Immunophenotypic and laboratory features of t(11;14)(q13;q32)-positive plasma cell neoplasms.

The t(11;14)(q13;32)-positive plasma cell neoplasms (PCNs) are common. In light of their lymphoplasmacytoid features and CD20 expression, we speculated that they may share laboratory features with B-cell lymphomas with plasmacytic differentiation (BCL-PCDs). We investigated flow cytometric CD19 and CD45 expression, DNA ploidy index and M-protein subtype in 416 t(11;14)-positive PCNs, as well as control groups (88 BCL-PCDs and 81 t(11;14)-negative PCNs). The plasma cells from the t(11;14)-positive PCNs were largely CD19-/CD45-, similar to the t(11;14)-negative PCNs and unlike the BCL-PCD plasma cells (p < .0001). 79% of the t(11;14)-positive PCNs were diploid, which was significantly more than in t(11;14)-negative PCNs (p < .0001) and significantly less than in the BCL-PCDs (p < .001). Although IgM secretion was common in BCL-PCDs (80%) and rare in PCNs (3%), most IgM PCNs (92%) were t(11;14)-positive. These findings may be helpful in evaluating specimens with clonal plasma cells in the reference laboratory setting.