Waldenstrom Macroglobulinemia / Plasma Cell Leukemia: A Diagnostic Dilemma

Waldenstrom macroglobulinemia (WM) is a subset of lymphoplasmacytic lymphoma and is
categorized under mature B-cell lymphoid neoplasm. This lymphoproliferative disorder is
characterized by infiltration of the bone marrow by a clonal lymphoplasmacytic infiltrate (≥10%) and
an IgM monoclonal gammopathy. WM infiltrate comprises B–lineage cells with predominance of small
lymphocytes, admixed with lymphoplasmacytoid cells, plasma cells and often increased mast cells.
This similar spectrum of cells, which is present in the bone marrow, may be present in the peripheral
blood as well. With marked plasmacytic differentiation, it may be challenging to differentiate it from
plasma cell leukemia. However, this differentiation is crucial for prognostication and therapeutic
decision-making. We present a case that manifested with fatigability and dyspnoea, and was
misdiagnosed as plasma cell leukemia on peripheral blood film and bone marrow morphology. It
finally turned out to be a case of Waldenstrom macroglobulinemia on cytoflorometry, highlighting
the role of elaborated workup and ancillary techniques to direct the accurate diagnosis and
management.