Remarkable response to radiation therapy with concurrent chemotherapy in Stewart–Treves syndrome

Stewart–Treves syndrome (STS) is a rare, cutaneous angiosarcoma associated with chronic lymphedema. The prognosis of this syndrome is extremely poor, with a median survival time of 5–8 months, if untreated. An 82-year-old Asian woman noticed a painless elastic mass with partial discoloration (purplish discoloration) on the left thigh. She had lower lymphedema for 15 years. Lesion biopsy and immunohistochemistry analysis led to the diagnosis of angiosarcoma, which was considered to be STS. She was referred to our department for concurrent chemoradiotherapy. Radiation therapy consisted of 25 daily fractions of 2 Gy each (prescription dose: 50 Gy). Concurrent chemotherapy consisted of 2 monthly cycles of docetaxel (75 mg/body on day 1) and recombinant interleukin-2 (700,000 units/body on days 1–5). She experienced acute adverse events such as Grade 2 dermatitis, Grade 2 anemia, and Grade 4 leukopenia. Posttreatment computed tomography images revealed that lesions had disappeared. Moreover, the accumulation patterns on positron emission tomography images were markedly weakened after the treatment. She exhibited no signs of recurrence for 4 years.