Definition

A rare disorder marked by the presence of an angiosarcoma (a malignant tumor of blood or lymph vessels) in a person with chronic (long-term) lymphedema. Lymphedema is a condition in which extra lymph fluid builds up in tissues and causes swelling, usually in the arm or leg. Stewart-Treves syndrome usually occurs in patients with breast cancer who develop chronic lymphedema after surgery to remove the breast and lymph nodes under the arm.