Clinical utility of morphology, immunohistochemistry, flow cytometry, and FISH analysis in monitoring of plasma cell neoplasms in the bone marrow

In this study, we examined clinical utility of morphology, immunohistochemistry (IHC), flow cytometric immunophenotyping (FC), and multiple myeloma (MM)-specific fluorescence in situ hybridization (FISH) in evaluation of disease burden in bone marrow (BM) of plasma cell neoplasms (PCNs). Of the 100 consecutive BM samples, 81 demonstrated PCN. CD138 IHC was the most sensitive technique to assess PCN burden compared to aspirate count or flow cytometry with mean values of 30 % (range 3–100), 19 (1–78), and 2.1 (0.01–33.2), respectively. CD138 IHC correlated well with the aspirate count (r2 = 0.5) but poorly with FC (r2 = 0.1). FC demonstrated the highest sensitivity in assessment of clonality 96 % (79/82), while morphology and IHC was positive in 84 % (71/82), FISH in 79 % (59/75) cases. Our results show that CD138 IHC is the most sensitive method for assessment of BM PCN burden whereas FC is the most sensitive method to establish the clonal nature of the PCN.