Angiomatosis of the breast is very rare. The presentations are including breast mass, skin discoloration and breast enlargement that mimic to angiosarcoma. The imaging could suggest non-specific vascular tumors. The histology should be obtained for the certain diagnosis. Surgical excision is the standard treatment. To our knowledge, this is the first case that preoperative radiation is given. Currently, radiation is occasionally used in benign condition. This case shows the successful result of preoperative radiation for achieving breast conserving surgery in large angiomatosis of the breast.