Hodgkin lymphoma, also called Hodgkin's disease, is one category of lymphoma, a cancer of the lymph system. Lymphoma begins when cells in the lymph system change and grow uncontrollably, which may form a tumor.
The lymph system is made up of thin tubes that branch out to all parts of the body. Its job is to fight infection and disease. The lymph system carries lymph, a colorless fluid containing lymphocytes (white blood cells). Lymphocytes fight germs in the body. B-lymphocytes (also called B cells) make antibodies to fight bacteria, and T-lymphocytes (also called T cells) kill viruses and foreign cells and trigger the B cells to make antibodies.
Groups of bean-shaped organs called lymph nodes are located throughout the body at different areas in the lymph system. Lymph nodes are found in clusters in the abdomen, groin, pelvis, underarms, and neck. Other parts of the lymph system include the spleen, which makes lymphocytes and filters blood; the thymus, an organ under the breastbone; and the tonsils, which are located in the throat.