Breast, Angiosarcoma

Angiosarcoma is a malignant vascular neoplasm of the breast that may arise as an idiopathic (primary) lesion or may arise secondary to local radiation to the breast for invasive breast carcinoma. Radiation-induced angiosarcoma usually arises 5-6 years after the completion of radiation treatment. Radiation induced angiosarcomas often have MYC amplification (55-65% of cases) which is not typically seen in non-radiation induced angiosarcoma or other atypical vascular lesions. Post-surgical arm edema after breast and axillary surgery for cancer increases the risk for angiosarcoma of the skin (called Stewart-Treves syndrome).

Histologically, angiosarcoma is characterized by irregular anastomosing vascular channels with irregular, infiltrative margins. Endothelial cells are pleomorphic and may increase to form papillary tufts within the vascular spaces.