Primary angiosarcoma of the ascending colon diagnosed after the discovery of intraoral tumor.

Here, we report a case of primary angiosarcoma of the ascending colon diagnosed after the discovery of an oral tumor. An 86-year-old woman presented to our hospital with severe anemia. Although she did not report any oral symptoms, an intraoral mass 15 mm in size with ulceration was observed. Since colonic tumors and osteolytic tumors in the maxilla and sacra were also identified by fluorodeoxyglucose (FDG)-positron emission tomography (PET), colonoscopy was performed. A semi-peripheral tumor with ulceration from the cecum to the ascending colon was detected. Biopsies of the oral cavity and colon revealed a poorly differentiated tumor, and multiple additional immunohistochemical stains were performed to confirm the diagnosis of angiosarcoma. Angiosarcoma progresses rapidly and has a very poor prognosis. Hence, although it is rare, angiosarcoma should always be considered in the differential diagnoses of malignancy of the gastrointestinal tract.