Stewart-Treves syndrome. A lethal complication of postmastectomy lymphedema and regional immune deficiency.

Lymphangiosarcoma is a fatal complication of postmastectomy lymphedema. The pathogenesis of lymphangiosarcoma in chronic lymphedema is a combination of two factors. First, the edematous region responds in a manner similar to "immunologically privileged sites." Second, because of its anatomic and physiologic properties, it is a favorable site for the development of mutant cell populations for reasons that are not fully understood. As a result, these mutant cells, with their genetically nonidentical antigens, escape recognition by the host's impaired immune surveillance mechanism. The failure to promote a sufficient immune response allows unrestricted tumor growth to take place, resulting in the ultimate death of the patient. Available therapeutic measures are equally unsatisfactory. Emphasis is placed on periodic examination of the lymphedematous extremity, aggressive treatment of established lymphedema and infections, and surgical preservation of lymphatic channels during breast cancer surgery.