Post-radiation Atypical Vascular Proliferation Mimicking Angiosarcoma Eight Months Following Breast-conserving Therapy for Breast Carcinoma.

Angiosarcoma is an aggressive tumor that most commonly presents on the scalp or face of elderly patients; however, it can develop in pateints with breast cancer following radiation and breast-conserving therapy, complicating 0.1 to 0.2 percent of such cases. Mammography and fine-needle aspiration, though often very useful in evaluating for breast carcinomas and cytological features, are often negative in early stages of angiosarcoma and difficult to interpret. We present the case of a 49-year-old Caucasian woman with a history of stage II invasive ductal carcinoma of the left breast who presented with a two-month history of increased firmness and tenderness in her left breast. On exam, her left breast had significant firmness and hardening of breast tissue with slight erythema of skin. Punch biopsy initially suggested angiosarcoma, but subsequent biopsies instead diagnosed an atypical vascular proliferation. This case represents a patient who presented with an atypical lesion concerning for angiosarcoma. Repeated biopsies were necessary to obtain the correct diagnosis. One biopsy may not be sufficient for distinguishing atypical vascular proliferation from angiosarcoma. We present this case to increase awareness of the difficulty in making this distinction.