Mammary angiosarcoma (AS) is an aggressive vascular tumor. It may appear de novo (primary angiosarcoma) or as a complication of radiotherapy (radiation-induced AS) or chronic lymphedema (Stewart-Treves syndrome). Our attention in this case study is focused on radiationinduced breast AS, a rare but severe long-term complication in the breast-preserving management of breast cancer, treated with breast-conserving surgery and radiotherapy. Contrary to what occurs in primary AS of the breast, which usually appears in women aged 30-50 years, radiation-induced breast AS affects older women (with a median age of 67-71 years) about 10.5 years after radiotherapy as treatment of primary breast cancer (the median onset latency varies from 5-10 years). The former is localized in the parenchyma, the latter in dermal and subcutaneous layers of the skin of radiated fields. The prognosis is poor with a high rate of relapse and an increased tendency to metastasis.