Flow cytometric (FC) enumeration of abnormal plasma cells (APCs) for diagnosis and prognostication of plasma cell dyscrasias (PCD) is challenging. We studied antigen expression in normal plasma cells (NPC) (N= 34) and APC in a series of unselected PCD (N= 59). NPC subpopulations often demonstrated CD19(-), CD20(+), CD45(-) or dim and CD56(+), an immunophenotype observed in PCD. However abnormal CD81 was only observed in APCs (APC detection sensitivity 95%; specificity 100%). We evaluated differences in antigen expression patterns among MGUS (N= 14), SMM ( N= 35) and MM (N= 10), finding the combination of CD45 and CD56 helpful in differentiating MGUS from SMM and MM (p= 0.0002).
- Monoclonal gammopathy of uncertain significance
- Multiple myeloma
- Normal plasma cell immunophenotype
- Smoldering multiple myeloma