Lymphedema, also known as lymphoedema and lymphatic edema, is a condition of localized fluid retention and tissue swelling caused by a compromised lymphatic system, which normally returns interstitial fluid to the bloodstream. Lymphedema commonly affects one of the arms or legs. In some cases, both arms or both legs may be affected. Some patients might experience swelling in the head, genitals, or chest. Lymphedema is incurable, but with the right treatment, it can be controlled.