Objective: To investigate the clinicopathological characteristics, diagnosis, differential diagnosis, biological behavior, prognosis, and treatment options of patients with primary epithelioid angiosarcoma(EA) of the bladder. Methods: The clinical manifestations, histological features, immunohistochemistry results and follow-up of a case of primary EA of the bladder were analyzed：Relevant literature from 1998 up to 2021 were searched on PubMed， and 17 cases with relatively complete clinical and follow-up data reported in the literature were summarized. Results: Primary EA of the bladder is rare, males tend to occur (male: female, 15∶3), the median age at presentation was 65 years (range, 32-85 years), and 8 patients (8/18 cases)(44.4%) had a clear history of radiotherapy to the pelvis. Most of them had local recurrence and distant metastasis within a short period of time. During follow-up 12 of the 18 cases (66.7%) died of disease, with a median survival of 6 months (range, 5 weeks to 19 months), 6 of 18 cases (33.3%) survived with or without disease, the follow-up time ranged from 3 months to 32 months. Histologically, the tumors were composed of sheets and sinusoid of highly atypical epithelioid cells. Tumor cells were pleomorphic with amphophilic cytoplasm. Mitotic activity was high and pathological mitotic could be seen. Intracytoplasmic lumens or vacuoles were present with occasional red blood cell within the vacuole. A hemorrhagic background was present. Immunostaining was positive for Vimentin, CD31, CD34, ERG, Fli-1 and CK-P, with partly positivity for CK7, Ki-67 hot spot about 40%. Conclusions: Bladder primary EA is rare. Some patients have a history of pelvis radiotherapy and are highly malignant. The therapentic effect and prognosis are not satisfied. Radical surgery combined with radiotherapy and chemotherapy and other treatment options may prolong survival. Because the immunohistochemical staining of cytokeratin is positive, it is easy to be misdiagnosed as high-grade cancer. It needs to be differentiated from post-radiotherapy sarcoma, sarcomatoid carcinoma, pseudoangiosarcomatoid urothelial carcinoma, epithelioid hemangioendothelioma, et al.
