Malignant lymphomas are cancers that arise from the lymphoid system, the complex network of cells and channels that runs throughout the body as a basic part of the immune system . Normally, the cells of the lymphoid system, lymphocytes , are either arranged in clusters—called lymph nodes or lymph glands—or they circulate through the bloodstream and the lymphatic channels to all the tissues of the body except the brain.
Cancers that develop within the lymphoid system—malignant lymphomas— may be found wherever normal lymphocytes go. They may occur in an isolated lymph node, a group of lymph nodes, in organs such as the stomach or intestine, the sinuses, bone, skin or any combination of these sites.
About 45,000 new cases of malignant lymphoma and lymphocytic leukemia (a lymphoid cancer that primarily involves the blood and bone marrow) will occur in 1994 in the United States. They are the seventh most common cause of cancer deaths. The increase in the incidence of non-Hodgkin's lymphoma between 1973 and 1987 was larger than the increase during that period for any other major cancer except melanoma and lung cancer.
Although lymphoma refers to any cancer of the lymphoid system, malignant lymphomas actually represent a variety of cancers ranging from slow-growing chronic diseases to rapidly progressive, acute diseases that may be
