A 54-year-old woman presented with a short history of multiple small purple 'spots' in the skin of the breast. She had a prior history of ipsilateral breast carcinoma treated with surgery and radiation 9 years earlier.

Pathologic Findings Each of these punch biopsy fragments shows a superficial dermal proliferation of mainly thin-walled vascular channels with angulated or notably dilated outlines. These vessels are architecturally atypical and are lined by a monolayer of endothelial cells with, in areas, mildly hyperchromatic protuberant nuclei. There is no endothelial multilayering or pleomorphism nor any discernible proliferative activity. In the adjacent dermis, one can appreciate scattered radiation fibroblasts. Immunostaining for MYC is negative.

ATYPICAL POST-RADIATION VASCULAR PROLIFERATION