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Lymphoma is a variety of cancer that originates in lymphocytes or, more rarely, of histiocytes. Collectively, these cell types form the reticuloendothelial system and circulate in the vessels of the lymphatic system. Just as there are many types of lymphocytes, so there are many types of lymphoma. Lymphomas are part of the broad group of diseases called hematological neoplasms. Traditionally, Lymphoma is classified as Hodgkin's lymphoma, discovered by Thomas Hodgkin in 1832, and non-Hodgkin's lymphoma (all other types of lymphoma). Modern classifications of lymphoma are more sophisticated than this simple scheme. Prevalence According to the U.S. National Institutes of Health, lymphomas account for about five percent of all cases of cancer in the United States, and Hodgkin's disease in particular accounts for less than one percent of all cases of cancer in the United States. Because the lymphatic system is part of the body's immune system, patients with weakened immune system, such as from HIV infection or from certain drugs or medication, also have a higher incidence of lymphoma. WHO Classification The WHO Classification is the latest classification of lymphoma, published by the World Health Organization in 2001. It was based upon the "Revised European-American Lymphoma classification" (REAL). This classification attempts to classify lymphomas by cell type, i.e. the normal cell type that most closely resembles the tumour. They are classified in three large groups: the B cell tumours, the T cell and natural killer cell tumours, Hodgkin lymphoma, and other minor groups: (ICD-O codes are provided where available) Mature B Cell Neoplasms
Mature T cell and Natural Killer (NK) Cell Neoplasms Hodgkin Lymphoma Immunodeficiency-Associated Lymphoproliferative Disorders Histiocytic and Dendritic Cell Neoplasms Working Formulation The Working Formulation, published in 1982, is primarily descriptive. It is still occasionally used, but has been superseded by the WHO classification, above. Low grade High grade Miscellaneous Other classification systems For Diagnosis, Etiology, Staging, Prognosis, and Treatment Please see separate links to Hodgkin's lymphoma and non-Hodgkin's lymphoma. See also | |||||||||
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