Effect of the sequence of pull of bone marrow aspirates on plasma cell quantification in plasma cell proliferative disorders.

Introduction: The evaluation of plasma cell (PC) compartment is influenced by the quality of bone marrow aspirate (BMA). Herein, we evaluated the impact of sequence of pull on quality of clinical assessment in plasma cell proliferative disorders (PCPDs).

Methods: Histomorphology along with smears from first pull and second pull BMA and flow cytometric immunophenotyping (FCMI) data from second pull aspirate were evaluated for cellularity and PC%.

Results: Of the 484 samples, BMA smears were adequate in 87.4% of first pull (median PC = 7%; IQR = 2-25%) and 51.2% of second pull samples (median PC = 2%; IQR = 0.5-12%; p < 0.001). Recovery of PC was least on FCMI (median PC = 0.59%; IQR = 0.14-3.07%), however, sample adequacy was met in 42.6% of samples with acquisition of ≥3 million events. Second pull smears under-reported PC% in 34% of newly diagnosed multiple myeloma (NDMM) (<10% PC) and 46% of MM on therapy (<5% PC), resulting in suboptimal assessment. Bone marrow biopsy (BMBx) was evaluated in a total of 309 cases (median PC = 10.0%; IQR 4.0-40.0%) with significantly higher numbers of BMPC% on BMBx compared with first pull smears (Mean ± 2SD: 25.9% ± 30.54 vs. 20.77% ± 20.20; p = 0.001).

Conclusion: First pull BMA smears were of superior quality but inadequate in one-tenth of samples. Second pull smears underreported PC% and recovery of PC compartment was poorest on FCMI. Concurrent bone marrow biopsy and use of the first pull sample for FCMI along with acquisition of a higher number of cells on FCMI may enhance the quality of assessment in PCPDs.