About the lymphatic system
The lymphatic system is made up of thin tubes and groups of tiny, bean-shaped organs called lymph nodes that are located throughout the body. The largest clusters of lymph nodes are found in the abdomen, groin, pelvis, underarms, and neck.
The lymphatic system carries lymph, a colorless fluid that contains a type of white blood cell called lymphocytes. Lymphocytes are part of the immune system and help fight germs in the body. B-lymphocytes, also called B cells, make antibodies that fight bacteria, while T-lymphocytes, also called T cells, kill viruses and foreign cells and trigger the B cells to make antibodies. Natural killer cells, or NK cells, also kill viruses and can directly kill cells infected by viruses.
Other parts of the lymphatic system include the spleen, which makes lymphocytes and filters the blood; the thymus, an organ under the breastbone; the tonsils, located in the throat; and the bone marrow. Bone marrow is the spongy red tissue inside bones that makes white blood cells, which are cells that fight infection; red blood cells, which are cells that carry oxygen throughout the body; and platelets, which are cells that help the blood clot.
About non-Hodgkin lymphoma
Lymphoma begins when B cells, T cells, or NK cells in the lymphatic system change and grow uncontrollably, sometimes forming a tumor. Hodgkin lymphoma is a specific type of lymphoma that is covered in another section of this website. Non-Hodgkin lymphoma (NHL) is a term that refers to a group of cancers of the lymphatic system that can have different symptoms and signs, findings on a physical examination, and treatments.
Because lymphatic tissue is found in most parts of the body, NHL can start almost anywhere and can spread to almost any organ. It most often begins in the lymph nodes, liver, spleen, or bone marrow, but it can also involve the stomach, intestines, skin, thyroid gland, brain, or any other part of the body.
It is very important to know which type and subtype of lymphoma has been diagnosed because this information helps doctors figure out the best treatment, as well as a patient’s chance of recovery or prognosis. More specific information can be found in the Subtypes of NHL section of this guide.
This guide covers NHL in adults. Learn more about childhood NHL.
Benign lymph nodeClick to Enlarge
These images used with permission by the College of American Pathologists.
Looking for More of an Overview?
If you would like additional introductory information, explore these related items. Please note these links take you to other sections on Cancer.Net:
- ASCO Answers Fact Sheet: Read a one-page fact sheet (available as a PDF) that offers an easy-to-print introduction to this type of cancer.
- Cancer.Net Patient Education Video: View a short video led by an ASCO expert in this type of cancer that provides basic information and areas of research.
- Cancer.Net En Español: Read about NHL in Spanish. Infórmase sobre linfoma no Hodgkin en español.