Lymphedema is a collection of fluid called lymph in the tissues of the body. It is often caused by cancer treatment, like surgery or radiation. Or it may be caused by cancer itself, such as when tumors press against lymph nodes or affect the lymph system. Other causes of lymphedema include infections, inflammatory conditions, obesity, and injury to the lymph nodes. Sometimes the cause isn't known.
Normally, lymph nodes trap bacteria and other substances as fluid flows through them. Then, the white cells in the body's defense, or immune, system can destroy the substances. But if there are few or no lymph nodes—or if the lymph system in an area of the body has been damaged—fluid can build up in the affected area. This can make you more likely to get an infection in that part of the body. This happens most often in an arm or leg.
Treatment focuses on managing lymphedema. This may include wearing compression garments to help reduce swelling and special massage to help drain lymph fluid from the area. It also includes self-care, such as watching closely for changes, protecting yourself from injury, and maintaining a healthy weight. Surgery is an option in some cases.