Angiosarcoma (AS) is a rare,aggressive tumour of endothelial origin occurring in various clinical settings,including idiopathic AS on the head and neck in elderly people,lymphoedema-associated AS,post-irradiation AS,soft-tissue AS,and various others. Despite the widespread use of radiation therapy in the treatment of breast carcinoma,AS developing in the wake of a radiation therapy is extremely infrequent. Although there is little doubt that radiation in therapeutic doses can induce sarcomas,quantification of that risk is complicated by many variables,among them chronic lymphoedema. We describe a 70-year-old woman in generally good health who presented with a 2-year history of a maculo-papular eruption on the skin of her right breast. There was no lymphoedema of the thoracic area. The lesions developed 3 years after she had undergone ipsilateral quadrantectomy for an invasive ductal carcinoma followed by 25 tangent field radiotherapy sessions on the breast. The oncological follow-up did not disclose local recurrence of the tumour or metastases of breast carcinoma. Histopathologic examination of a papule was diagnostic for AS. In addition,signs of chronic radiation dermatitis were found in the biopsy specimens. The patient underwent monthly cycles of chemotherapy with intravenous doxorubicin with partial remission of the affected area after 24months,followed by the occurrence of livermetastases and exitus 30months after diagnosis. From the review of the literature,it appears that post-irradiation mammary AS mainly affects women over 60 who have undergone breast-sparing surgery and that it is usually associated with axillary lymphadenectomy. Whereas the role of lymphoedema does not seem relevant to the pathogenesis of this malignancy,the association with chronic radiation dermatitis in our case reinforces the supposed role of radiation in the development of this tumour. Onset of AS should be taken into consideration when treating patients who developmultiple lesions on the skin above the irradiated area,even many years after the therapy. Angiosarcoma (AS) is a rare, aggressive tumor of endothelial origin occurring in various clinical settings, including idiopathic AS on the head and neck in elderly people, lymphoedema-associated AS, post-irradiation AS, soft-tissue AS, and various others. Despite the widespread use of radiation therapy in the treatment of breast carcinoma, AS developing in the wake of a radiation therapy is extremely infrequent. Though there is little doubt that radiation in therapeutic doses can induce sarcomas, quantification of that risk is complicated by many variables , among them chronic lymphoedema. We describe a 70-year-old woman in generally good health who presented with a 2-year history of a maculo-papular eruption on the skin of her right breast. There was no lymphoedema of the thoracic area. The lesions developed 3 years after she had undergone ipsilateral quadrantectomy for an invasive ductal carcinoma followed by 25 tangent field radiotherapy sessions on the breast. The oncological follow-up di d. not disclose local recurrence of the tumor or metastases of breast carcinoma. Histopathologic examination of a papule was diagnostic for AS. From the review of the literature, it appears that post-irradiation mammary AS mainly affects women over 60 who have undergone breast-sparing surgery and that Whereas the role of lymphoedema does not seem relevant to the pathogenesis of this malignancy, the association with chronic radiation dermatitis in our case reinforces the supposed role of radiation in the development of this tumour. Onset of AS should be taken into consideration when treating patients who developmultiple lesions on the skin above the irradiated area, even many years after the therapy.