Clinicopathological features and management of IgM multiple myeloma and Waldenstrom macroglobulinemia.

Waldenström macroglobulinemia (WM) is the most common malignancy associated with an IgM paraprotein, but in rare cases, a clonal IgM may be the result of IgM multiple myeloma (IgM-MM). Although there are some overlapping features associated with these two entities, there are specific characteristics that can help differentiate IgM-MM from WM. In each patient a thorough clinical, pathologic, and genomic evaluation is required to distinguish these conditions and allow for accurate diagnosis and appropriate treatment.