Cutaneous angiosarcoma is extremely rare, accounting for less than 1% of all sarcomas. Most of the cases are directly diagnosed according to clinical information and surgical-pathological examination, without imaging studies. We report a rare case of cutaneous angiosarcoma in the left upper arm with a history of postoperative radiotherapy for left breast cancer 24 years previously. Magnetic resonance imaging and angiography were performed to obtain additional reference and imaging results.