Peripheral neuropathy occurs in 10% of patients. Enlargement of the lymph nodes, spleen, and/or liver are present in 30–40% of cases. Other possible signs and symptoms include blurring or loss of vision, headache, and (rarely) stroke or coma. Causes
Waldenström macroglobulinemia is characterized by an uncontrolled clonal proliferation of terminally differentiated B lymphocytes. The most commonly associated mutations, based on whole-genome sequencing of 30 patients, are a somatic mutation in MYD88 (90% of patients) and a somatic mutation in CXCR4 (27% of patients). CXCR4 mutations cause symptomatic hyperviscosity syndrome and high bone marrow activity characteristic of the disease. However, CXCR4 mutation is not associated with splenomegaly, high platelet counts, or different response to therapy, questioning the relevance of CXCR4 in treating patients. An association has been demonstrated with the locus 6p21.3 on chromosome 6. There is a two- to threefold increased risk of Waldenström macroglobulinemia in people with a personal history of autoimmune diseases with autoantibodies, and a particularly elevated risk associated with liver inflammation, human immunodeficiency virus, and rickettsiosis.There are genetic factors, with first-degree relatives of Waldenström macroglobulinemia patients shown to have a highly increased risk of also developing the disease. There is also evidence to suggest that environmental factors, including exposure to farming, pesticides, wood dust, and organic solvents, may influence the development of Waldenström macroglobulinemia. Genetics
Although believed to be a sporadic disease, studies have shown increased susceptibility within families, indicating a genetic component. A mutation in gene MYD88 has been found to occur frequently in patients.
A low level of neutrophils (a specific type of white blood cell) may also be found in some individuals with Waldenström macroglobulinemia.Chemistry tests include lactate dehydrogenase (LDH) levels, uric acid levels, erythrocyte sedimentation rate (ESR), kidney and liver function, total protein levels, and an albumin-to-globulin ratio. The ESR and uric acid level may be elevated. Creatinine is occasionally elevated and electrolytes are occasionally abnormal. A high blood calcium level is noted in approximately 4% of patients. The LDH level is frequently elevated, indicating the extent of Waldenström macroglobulinemia–related tissue involvement. Rheumatoid factor, cryoglobulins, direct antiglobulin test and cold agglutinin titre results can be positive. Beta-2 microglobulin and C-reactive protein test results are not specific for Waldenström macroglobulinemia. Beta-2 microglobulin is elevated in proportion to tumor mass. Coagulation abnormalities may be present. Prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen tests should be performed. Platelet aggregation studies are optional. Serum protein electrophoresis results indicate evidence of a monoclonal spike but cannot establish the spike as IgM. An M component with beta-to-gamma mobility is highly suggestive of Waldenström macroglobulinemia. Immunoelectrophoresis and immunofixation studies help identify the type of immunoglobulin, the clonality of the light chain, and the monoclonality and quantitation of the paraprotein. High-resolution electrophoresis and serum and urine immunofixation are recommended to help identify and characterize the monoclonal IgM paraprotein. The light chain of the monoclonal protein is usually the kappa light chain. At times, patients with Waldenström macroglobulinemia may exhibit more than one M protein. Plasma viscosity must be measured.