Along the network of vessels are groups of small, bean-shaped organs called nodes. Lymph nodes are clustered in the neck, under the arms, in the groin and abdomen. The lymph nodes make and store infection-fighting cells. The spleen, thymus and tonsils are also part of the lymph system. Like all types of cancer, lymphomas are diseases of the body's cells.
Healthy cells grow, divide, and replace themselves in an orderly manner.
When lymphoma occurs, cells in the lymphatic system grow abnormally. They divide too rapidly and grow without any order or control. Too much tissue is formed and tumors begin to grow. Because there is lymph tissue in many parts of the body, the cancer cells may spread to other organs such as the liver or spleen or into the bone marrow. Lymphomas are divided into Hodgkin's and non-Hodgkin's lymphomas.