Overview of Non-Hodgkin's Lymphoma (NHL)
Lymphomas are cancers of the lymphatic systemthe body's blood-filtering tissues that help to fight infection and disease. Like other cancers, lymphomas, occur when cells divide too much and too fast. Growth control is lost, and the lymphatic cells may overcrowd, invade, and destroy lymphoid tissues and metastasize (spread) to other organs.
There are two general types of lymphomas: Hodgkin's disease (named after Dr. Thomas Hodgkin, who first recognized it in 1832) and non-Hodgkin's lymphoma. The lymphatic tissue in Hodgkin's disease contains specific cells (called Reed-Sternberg cells) that are not found in any other cancerous lymphomas or cancers. These cells distinguish Hodgkin's disease (HD) from non-Hodgkin's lymphoma (NHL).
Anatomy of the Lymphatic System
The lymphatic system, which is the target of lymphomas, includes the lymph nodes and other organs that make up the immune and blood-forming (hematopoietic) elements of the body.
The lymph nodes are oval, pea-sized organs. They are found beneath the skin along the route of large blood vessels, and are grouped in areas such as the neck, underarms, groin, abdomen (trunk), and pelvis (hips). Lymph nodes are linked throughout the body by narrow tubes called lymphatic vessels.
These vessels carry lymph (colorless liquid that is collected from the body's tissues), chyle (milky fluid taken from food in the intestine during digestion), lymphocytes (specialized white blood cells), and other blood cells. The lymphatic fluids and lymphocytes ultimately are funneled back into the bloodstream through a connection in the left upper chest.
Other organs that contain lymphatic tissue and can be affected by lymphoma include the following:
- Spleen ("ductless gland" located on the left side of the body under the lower rib cage that makes lymphocytes and other infection-fighting cells, stores healthy blood cells, and filters the blood)
- Thymus gland (gland located in front of the heart that produces immature T-cells that, when mature, are involved in immune system responses)
- Bone marrow (inner region of the bones)
- Adenoids (lymphatic tissue in the post-nasal area)
- Tonsils (rounded mass of lymphatic tissue at the back of the throat)
Both Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) begin in lymphatic tissues and can invade other organs. However, NHL is much less predictable than HD and is more likely to spread to areas beyond the lymph nodes.
Anatomically, lymphoma is composed of malignant lymphocytes. Lymphocytes are a normally occurring part of the white blood cell series. The lymphocyte population can be simplistically divided into B-cells, T-cells, and null cells. The job of B-cell lymphocytes is to participate in the immune system by producing antibodies. The job of the T-cell lymphocytes is to direct the participation of B-cells and other cell types in an overall immune response; they are the conductors of the immune system. Lymphomas are the malignant counterpart of these normal cells.