What is AIDS Related Lymphoma?AIDS-related lymphoma is a disease in which malignant (cancer) cells form in the lymph system of patients who have acquired immunodeficiency syndrome (AIDS). AIDS is caused by the human immunodeficiency virus (HIV), which attacks and weakens the body's immune system. The immune system is then unable to fight infection and diseases that invade the body. People with HIV disease have an increased risk of developing infections, lymphoma, and other types of cancer. A person with HIV disease who develops certain types of infections or cancer is then diagnosed with AIDS. Sometimes, people are diagnosed with AIDS and AIDS-related lymphoma at the same time. For information about AIDS and its treatment, please see the AIDSinfo Web site. Lymphomas are cancers that affect the white blood cells of the lymph system, part of the body's immune system. Lymph : -Colorless, watery fluid that travels through the lymph system and carries white blood cells called lymphocytes. Lymphocytes protect the body against infections and the growth of tumors. Lymph vessels : - A network of thin tubes that collect lymph from different parts of the body and return it to the bloodstream.