Angiosarcoma of the breast is a rare form of cancer that occurs in the breast and in the tissue of the upper arms. There are two types of angiosarcoma; primary and secondary. Primary angiosarcoma is diagnosed in women who have never been diagnosed with breast cancer before. Secondary angiosarcoma is diagnosed in women who have had breast cancer before, and this cancer may be caused by radiation therapy. Symptoms of this condition include: thickening of the breast wall, rash-like symptoms, and discoloration of the breast skin tissue. Angiosarcoma of the breast can grow and spread quickly, so it is important to diagnose early. Mammograms, ultrasounds, MRIs, or biopsies can diagnose this condition. Treatment typically involves surgery or chemotherapy.