Modern possibilities for diagnosing and tumor clone monitoring, determined by multicolor flow cytometry, in Waldenstrom’s macroglobulinemia

Waldenstrom’s macroglobulinemia (WM) is a subtype of lymphoplasmacytic lymphoma that combines lymphoplasmacytic lymphoma substrate in the bone marrow and monoclonal immunoglobulin M secretion in the blood. WM diagnosis is a complex process, which is due to both the heterogeneity of tumor populations and similarity to other B-cell lymphomas. The WM tumor cell clone has unique immunophenotypic characteristics and is represented by two aberrant populations from one tumor clone: clonal B-lymphocytes and plasma cells. Detection and characterization of these two aberrant populations seems possible only using multicolor flow cytometry. Bone marrow cell immunophenotyping by flow cytometry establishes the tumor cell immunophenotype, which plays a key role in the differential diagnosis of WM from other types of small cell lymphomas, as well as when other methods are uninformative.To assess the depth of therapy response, instrumental and laboratory methods are used, including positron emission tomography combined with computed tomography to monitor the size and spread of the tumor mass, immunochemical testing to measure the monoclonal immunoglobulin M secretion, molecular bone marrow research for the presence of MYD88 gene mutations, as well as bone marrow cell immunophenotyping by multicolor flow cytometry. Currently, it is especially important to study the dynamics of minimal residual disease in WM using the capabilities of multicolor flow cytometry.