Stewart Treves syndrome is a rare angiosarcoma that develops in people with long-standing lymphedema. Most affected people have a history of breast cancer that was treated with a radical mastectomy. Early signs of the condition vary and may include purplish patches that develop into skin nodules, a mass under the skin, or a poorly healing eschar with recurrent bleeding and oozing. The exact underlying cause of the condition is poorly understood. Although Stewart Treves syndrome is always associated with long-standing lymphedema, other unknown factors also appear to contribute to the development of the condition. Early diagnosis and aggressive surgical treatment may improve the long-term outlook of the condition. Chemotherapy, radiation therapy, and immunotherapy continue to be studied as possible treatment options and may be recommended in some cases.

• A purplish patch that develops into a skin nodule
• A mass under the skin
• A poorly healing eschar with recurrent bleeding and oozing

The condition may begin as multiple, separate skin lesions that can grow together and form an enlarging lesion. As Stewart Treves syndrome advances, the skin over the lesion may become thin and ulcerate, leading to recurrent episodes of bleeding and infection.

Stewart Treves syndrome is a very aggressive form of cancer and often spreads quickly to other parts of the body, especially the lungs.

Of note, certain types of lymphedema , such as that caused by cardiac or renal disease, is not associated with Stewart Treves syndrome. Therefore, lymphedema alone is not sufficient to cause the condition. This suggests that other factors such as a genetic predisposition may also be present in affected people.

Stewart Treves syndrome is generally treated with surgery. Early diagnosis with amputation or wide local excision offers the best chance for long-term survival. Chemotherapy, radiation therapy, and immunotherapy continue to be studied as possible treatment options and may be recommended in some cases.

Unfortunately, the long-term outlook (prognosis) for Stewart Treves syndrome is generally poor. The condition is often extremely aggressive and has a tendency to metastasize early to many different areas of the body. Early diagnosis and surgical treatment may improve prognosis, but local recurrence following surgery is common. If the condition is left untreated, affected people have an average survival of 5-8 months. Studies suggest that the 5-year survival with treatment is between 8.5% and 16%.