Masson's tumor of the breast: Rare differential for new or recurrent breast cancer-Case report, pathology, and review of the literature.

A 66-year-old woman had a new left breast mass with a prior history of a stage IIIC left breast cancer. She had excision of the mass. The pathology noted intravascular papillary endothelial hyperplasia (IPEH) also known as Masson's tumor. Although a benign lesion, this remains in the differential of breast lesions with vascular morphology. IPEH has been described at multiple sites throughout the body. It must be distinguished from angiosarcoma. Although Masson's tumor has been previously documented in the breast, prior treatment for breast cancer presents a diagnostic dilemma. Treatment for the breast cancer may be a contributing event for Masson's tumor.