Flow cytometric sensitivity and characteristics of plasma cells in patients with multiple myeloma or its precursor disease: influence of biopsy site and anticoagulation method

Flow cytometry has increasing relevance for prognosis in myeloma and precursor disease (monoclonal gammopathy of unknown significance/smoldering myeloma), yet it has been reported that plasma cell enumeration by flow varies depending on the quality of marrow aspirate and field biopsied in patchy disease. We demonstrated increased sensitivity of flow over immunohistochemistry in abnormal-plasma cell detection in monoclonal gammopathy (n = 59)/smoldering myeloma (n = 87). We prospectively evaluated treatment-naive smoldering myeloma (n = 9)/myeloma (n = 11) patients for the percentage of abnormal plasma cells/total plasma cell compartment, plasma cell viability/infiltration and flow immunophenotype depending on anticoagulant use, biopsy site and pull sequence in uni-and-bilateral bone marrow biopsies and aspirates. We found no statistical difference regarding the percentage of abnormal plasma cells, their immunophenotype or number/distribution in marrow samples even when obtained by different sequence in aspirates, or anticoagulants (p > 0.05). Our results show that plasma cell enumeration and immunophenotyping by flow cytometry is consistent under different conditions in these populations.