Histopathological diagnosis is often challenging, given the morphological similarity to other vascular lesions. Immunohistochemistry plays a fundamental role in diagnostic confirmation, being essential in the differentiation of angiosarcoma from other vascular lesions, as observed in this case. Positivity for CD31, CD34, and ERG indicated two diagnostic possibilities, namely epithelioid hemangioendothelioma or angiosarcoma. This evidence concerns the gene PECAM1 and angiosarcoma.