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Myeloproliferative disorder of B-lymphocytes producing abnormal plasma cells that secrete excess IgM causing hyperviscosity (thickening) of blood. WM is defined as a lymphoplasmacytic lymphoma (9671/3) with bone marrow involvement and IgM of any concentration. A significant subset of lymphoplasmacytic lymphoma patients has WM.
Neoplasm of small B lymphocytes, plasmacytoid lymphocytes, and plasma cells, involving bone marrow, lymph nodes, spleen; usually lacking CD5; serum monoclonal protein of IgM with consequent hyperviscosity symptoms.
Waldenstrom Macroglobulinemia (WM) is a subset of lymphoplasmacytic lymphoma. Patients with WM have IgM (immunoglobulin M) in their blood and/or bone marrow. IgM is also called IgM monoclonal gammopathy. 15-30% of WM patients have splenomegaly, hepatomegaly, and/or adenopathy. There will also be an increased number of lymphocytes in the blood. A familial disposition may exist in up to 20% of patients. It tends to be diagnosed at a younger age than other lymphoplasmacytic lymphomas.
Definitive Diagnostic Methods
Somatic hypermutations in V regions of IG genes (IgM), t(9;14)(p13;q32) in 50% of cases
6q deletion in 50% of cases
Trisomy 4 in 20% of cases
WM has a homogenous gene expression profile other than 6q deletion, more similar to CLL and normal B-cells than to myeloma