Waldenström's macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by the malignant accumulation of IgM-producing lymphoplasmacytic cells in the bone marrow and other organs. Recurrent somatic mutations in MYD88 and CXCR4 give the malignant cells a survival advantage through an apoptosis escape mechanism (i.e., immortalization).