Lymphoma

Lymphoma is a general term for a variety of cancer that begins in the lymphatic system. In technical terms, lymphoma denotes malignancies of 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.

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 have moved away from this artificial division.

Classification

Working Formulation
The Working Formulation, published in 1982, is primarily descriptive but remains the most widely used classification of non-Hodgkin lymphoma today.

Low Grade
Malignant Lymphoma, small lymphocytic (chronic lymphocytic leukemia)
Malignant Lymphoma, follicular, predominantly small cleaved cell
Malignant Lymphoma, follicular, mixed (small cleaved and large cell)

Intermediate Grade
Malignant Lymphoma, follicular, predominantly large cell
Malignant Lymphoma, diffuse, small cleaved cells
Malignant Lymphoma, diffuse, mixed (small and large cells)
Malignant Lymphoma, diffuse large cells

High Grade
Malignant Lymphoma, large cell, immunoblastic
Malignant Lymphoma, lymphoblastic
Malignant Lymphoma, small non-cleaved cells (Burkitt's lymphoma)

Miscellaneous
Composite
Mycosis fungoides
Histiocytic
Extramedullary plasmacytoma
Unclassifiable

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.