Post-radiation vascular lesions of the breast.

Post-radiation vascular lesions are a rare complication most commonly seen in patients previously treated for breast cancer. The main two entities include angiosarcoma (AS), which are malignant tumors that have a poor prognosis, and atypical vascular lesions (AVL), which typically behave in a benign manner and only rarely progress to angiosarcoma. The overall incidence of these lesions is low, but it appears to be increasing. Histopathologic distinction of AVL and AS is essential due to different clinical outcomes and treatment. However, due to the occasional existence of overlapping clinical and histopathologic features, it may be sometimes difficult to render a definite diagnosis, particularly in small biopsies. Ancillary techniques are, in general, of little help for separating the borderland cases but, in some instances, immunohistochemical study (IHC) for Ki67 and IHC or fluorescence in situ hybridization analysis for MYC may help in the diagnosis of angiosarcoma. Herein we discuss the clinical characteristics, histopathologic features, management strategies, and outcome of these lesions, with special emphasis on their differential diagnosis.