shown to be reliable. it is also applicable to patients on a rituximab-based treatment regimen. an additional predictive factor is elevated serum lactate dehydrogenase (ldh). epidemiology of cancers involving the lymphocytes, 1% of cases are waldenström macroglobulinemia. a rare disorder, there are fewer than 1,500 cases occurring in the united states annually. the median age of onset is between 60 and 65 years, with some cases occurring in late teens. notable victims of the disease include dancer/choreographer gower champion, who died of the disease in 1980, aged 61; and former french president georges pompidou. history waldenström macroglobulinemia was first described by jan g. waldenström (1906–1996) in 1944 in two patients with bleeding from the nose and mouth, anemia, decreased levels of fibrinogen in the blood (hypofibrinogenemia), swollen lymph nodes, neoplastic plasma cells in bone marrow, and increased viscosity of the blood due to increased levels of a class of heavy proteins called macroglobulins. for a time, waldenström macroglobulinemia was considered to be related to multiple myeloma because of the presence of monoclonal gammopathy and infiltration of the bone marrow and other organs by plasmacytoid lymphocytes. the new world health organization (who) classification, however, places waldenström macroglobulinemia under the category of lymphoplasmacytic lymphomas, itself a subcategory of the indolent (low-grade) non-hodgkin lymphomas. since the 1990s, there have been significant advances in the understanding and treatment of waldenström macroglobulinemia.