Figure 2. Flow cytometry analysis on peripheral blood, revealed a significant population of circulating plasma cells (blue) (65% of total analyzed cells). These circulating plasma cells were found in an SSC low/CD45 dim-negative gate, with strong expression of CD38 and CD138. Interestingly, these cells expressed CD19 and surface lambda and some plasma cells exhibited dim CD20 and CD56. There were polyclonal mature B lymphocytes (purple). These cells did not exhibit any markers of immaturity. Flow cytometry analysis of the bone marrow (not shown here) revealed similar proportions of plasma cells with the same immunophenotype.*Cells in the peripheral blood were characterized by flow cytometry using tubes to evaluate plasma cells (Tube 1), B cells (Tube 2), and blasts (Tube 3). Tube 1 (plasma cells): CD20-BB515 (Becton-Dickinson)/ CD117-PE (Biolegend)/ CD38-PerCPCy5.5 (Biolegend)/ CD19-PECy7 (Biolegend)/ CD138-APC (Biolegend)/ CD45-APCFire750 (Biolegend)/ CD56-BV421 (Biolegend). Tube 2 (B cells): CD79b-FITC (Biolegend)/ slambda-PE (Dako)/ CD20-PerCPCy5.5 (Biolegend)/ CD19-PECy7 (Biolegend)/ skappa-APC (Dako)/ CD10-APCFire750 (Biolegend)/ CD5-BV421 (Biolegend)/ CD3-BV510 (Biolegend). Tube 3 (cytoplasmic blasts): nTdT-FITC (Dako)/ cIgM-PE (Dako)/ HLA-DR-PerCPCy5.5/ CD10-PECy7 (Biolegend)/ CD7-APC (Biolegend)/ CD45-APCFire750 (Biolegend)/ CD19-BV421 (Biolegend)/ CD34-BV510 (Biolegend).