Angiosarcoma of breast, light micrograph. Angiosarcomas of the breast may be primary or occur following surgical and/or radiation treatment for breast cancer. It accounts for less than 0.1% of all primary malignancies of the breast. It appears as ill-defined, deep-seated, spongy, haemorrhagic lesion in the breast parenchyma. The image shows capillary-type growth in a low-grade angiosarcoma of the breast. It consists of a dense proliferation of small capillary-type vessels infiltrating adipose tissue of the breast.