Non-Hodgkin's lymphoma (NHL) is cancer of the cells of the lymphatic system. In non-Hodgkin's lymphoma, cells in the lymphatic system divide and grow without order or control, or old cells do not die as cells normally do.

Non-Hodgkin's lymphoma can start almost anywhere in the body. It may occur in a single lymph node, a group of lymph nodes, or an organ such as the spleen. NHL can spread to almost any part of the body, including the liver, bone marrow, and spleen.

The incidence of non-Hodgkin’s lymphoma has increased over the years, but experts don’t know what causes NHL. It may be that a "trigger," such as exposure to something in the environment, causes rapid cell growth that is not normal, and this abnormal cell growth develops into NHL. NHL is not contagious.

The most common symptom of non-Hodgkin's lymphoma is a painless swelling of the lymph nodes in the neck, underarm, or groin. Other symptoms may include unexplained fever; night sweats; fatigue; weight loss; and red, itchy patches on the skin.

The chances of cure with non-Hodgkin's lymphoma depend on the stage of the cancer and what the cells look like under the microscope (histology) when the lymphoma is diagnosed. NHL is often treated with radiation or chemotherapy.

Non-Hodgkin's lymphoma is different from and occurs more frequently than Hodgkin's lymphoma.