728 DOI: 10.1309/AJCP1GYI7EHQYUYK © American Society for Clinical Pathology Hematopathology / Immunophenotyping and Residual Disease in Myeloma Flow Cytometric Immunophenotyping and Minimal Residual Disease Analysis in Multiple Myeloma

Presence of normal plasma cells (PCs), hemodilution of bone marrow aspirate, and changes in the immunophenotype are important considerations in minimal residual disease (MRD) assessment in multiple myeloma (MM). We evaluated 124 subjects—107 with MM, 11 with Hodgkin lymphoma, and 6 allogeneic stem cell transplantation donors—for the immunophenotype of neoplastic, reactive, and normal PCs respectively. Of the patients with MM, 36 were evaluated for MRD and 23 for a change in immunophenotype after chemotherapy. The immunophenotype of normal and reactive PCs was similar and differed from that of neoplastic PCs with respect to CD19, CD45, CD56, CD52, CD20, and CD117. At least 2 antigens were aberrantly expressed in all cases and 3 in 90.7 % o