A limited plasma cell flow cytometry panel with reflex CD138 immunohistochemistry is an optimal workflow process for evaluating plasma cell neoplasms in bone marrow specimens

Objectives: To determine the optimal workflow combination of flow cytometry (FC) and immunohistochemistry tests for efficient and cost-effective evaluation of plasma cell (PC) neoplasms (PCNs) in bone marrow (BM) specimens. Methods: Various workflow combinations of immunohistochemistry and FC for 4,031 BM specimens worked up for PCNs were compared. Turnaround time (TAT), immunohistochemistry usage, technical charges, and addendum/amendment rates were compared between periods to determine the optimal workflow combination. Results: Five distinct workflow periods were identified, with varying combinations of full or limited FC panels for assessing PC clonality and CD138/κ/λ immunohistochemistry for PC quantification. Replacement of full FC with limited FC was associated with significant reductions in TAT and number of immunostains performed per case. Elimination of immunohistochemistry on cases determined to be polyclonal by FC also resulted in significant reductions in immunohistochemistry usage and significant cost savings. Conclusions: Assessment of PC clonality using a limited FC panel followed by reflex CD138 immunohistochemistry on cases that are monoclonal by FC provides an optimal and cost-effective workflow for evaluating PCNs in BM samples.