Non-Hodgkin's lymphoma (also called NHL) is cancer that begins in the lymphatic system. To understand this disease, it is helpful to know about the lymphatic system.

The Lymphatic System

The lymphatic system is part of the body's immune system. The immune system fights infections and other diseases.

In the lymphatic system, a network of lymph vessels carries clear fluid called lymph. Lymph vessels lead to small, round organs called lymph nodes. Lymph nodes are filled with lymphocytes (a type of white blood cell). The lymph nodes trap and remove bacteria or other harmful substances that may be in the lymph. Groups of lymph nodes are found in the neck, underarms, chest, abdomen, and groin.

Other parts of the lymphatic system include the tonsils, spleen, and thymus. Lymphatic tissue is also found in other parts of the body including the stomach, skin, and small intestine.

Lymphatic system.

Non-Hodgkin's Lymphoma

There are many types of non-Hodgkin's lymphoma. All types of lymphoma begin in cells of the lymphatic system. Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place. Sometimes this process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Non-Hodgkin's lymphoma begins when a lymphocyte (a B cell or T cell) becomes abnormal. Usually, non-Hodgkin's lymphoma starts in a B cell in a lymph node. The abnormal cell divides to make copies of itself. The new cells divide again and again, making more and more abnormal cells. The abnormal cells are cancer cells. They do not die when they should. They do not protect the body from infections or other diseases. Also, the cancer cells can spread to nearly any other part of the body.