Cancer Treatment Today

MGUS is a pre-myeloma condition, characterized by an asymptomatic increase in monoclonal proteins. Multiparameter flow cytometry (MFC) has become standard in the management of patients with plasma cell (PC) dyscrasiasIt plays a significant role during the differential diagnostic work-up because of its fast and conclusive readout of PC clonality, and simultaneously provides prognostic information in most monoclonal gammopathies. From a clinical point of view, one of the most evident roles of routine MFC is during patients’ differential diagnostic work-up. First, to distinguish between prominent but reactive and benign plasmacytosis vs. clonal and potentially malignant PC dyscrasias. Second, to recognize B-cell non-Hodgkin lymphomas (B-NHL) with extensive plasmacytic differentiation such as lymphoplasmacytic lymphoma (LPL, WM) or marginal zone lymphoma (MZL). The distinction can be made by careful identification of small B-cell clones that may be below the limit of detection of morphology or immunohistochemistry (IHC), together with comprehensive evaluation of the phenotypic profile of tumor PCs.26 Third, to confirm the diagnosis of rare IgM myeloma cases based on distinct PC phenotype from other IgM producing B-cell disorders.25 Fourth, to help discriminate between MGUS vs SMM vs active MM based on the percentage of nPCs within the bone marrow PC (BMPC) compartment. It can also be sued to provide prognostic information.

Jelinek T, Bezdekova R, Zatopkova M, et al. Current applications of multiparameter flow cytometry in plasma cell disorders [published correction appears in Blood Cancer J. 2018 Jan 19; 8(1): e621]. Blood Cancer J. 2017; 7(10): e617. Published 2017 Oct 20. doi: 10.1038/bcj.2017.90

Ernesto Pérez-Persona , et al, New criteria to identify risk of progression in monoclonal gammopathy of uncertain significance and smoldering multiple myeloma based on multiparameter flow cytometry analysis of bone marrow plasma cells. Blood (2007) 110 (7): 2586–2592.
NCCN Multiple Myeloma 2021