Multiple colonic epithelioid angiosarcoma: a case report and review of literature

Primary angiosarcoma of the large intestine is an extremely rare and aggressive malignancy. Epithelioid angiosarcoma (EAS) is a variant of angiosarcoma and tends to be deep-seated. Because of its rarity and morphological similarity, EAS may be misdiagnosed as poorly-differentiated carcinoma, especially in limited tissue biopsy. Here, a case of colonic EAS in a 77-year-old female presenting as melena is reported to define the clinicopathologic features of the rare disease with emphasis on differential diagnosis. By colonoscopy, multiple masses were found in the sigmoid and transverse colon. Histological examination showed epithelioid neoplastic cells with prominent nucleoli, which were morphologically similar to poorly-differentiated carcinoma. Immunohistochemical study revealed that the neoplastic cells were positive for both epithelial markers (AE1/AE3, CK7, and P63) and specific endothelial markers (CD31 and ERG). These results suggest that a panel of immune markers including endothelial markers should be used for differential diagnosis in colorectal epithelioid tumors.