Lymphatic vessels carry lymph, a colorless, watery fluid that contains infection-fighting cells called lymphocytes. Along this network of vessels are groups of small, bean-shaped organs called lymph nodes that filter the lymph as it passes through the nodes. Clusters of lymph nodes are found in the underarm, groin, neck, and abdomen. Other parts of the lymphatic system are the spleen, thymus, tonsils, and bone marrow. Like all types of cancer, Hodgkin's disease affects the body's cells.
Healthy cells grow, divide, and replace themselves in an orderly manner.
This process keeps the body in good repair. In Hodgkin's disease, cells in the lymphatic system grow abnormally and can spread to other organs. As the disease progresses, the body is less able to fight infection. Hodgkin's disease is rare. It accounts for less than 1 percent of all cases of cancer in this country.