We report a case of a 44-year-old woman with primary angiosarcoma of the left breast. An excisional biopsy was performed initially and the mass was interpreted as angiosarcoma. The pre-operative staging provided no evidence of metastasis. The patient then underwent a left mastectomy with the placement of an expandable prosthesis. For 3 months the prosthesis was progressively expanded to the desired size and it was then replaced with a permanent one. Primary angiosarcoma of the breast is a rare and often misdiagnosed disease. Treatment options are numerous and conflicting. The diagnostic approach and treatment options from the literature are presented and discussed.