Abstract: Objective:To investigate the clinical and pathological features, diagnosis and differential diagnosis, treatment and prognosis of pelvic solitary fibrous tumor.Methods:The clinical and pathological features, diagnosis and differential diagnosis, treatment and prognosis of pelvic solitary fibrous tumor in a case were explored.Results:Complete capsule, smooth surface, gray cut-off and soft texture of tumor were observed under naked eye.Under microscopy, the tumor was mainly composed of spindle cells, mild dysplasia, coarse nuclear chromatin and uneven mitosis in tumor cells were detected, the tumor cells were alternatively arranged by hypercellularity and hypocellularity, and the necrosis with low potential malignancy, rich interstitial blood vessels and a large number of collagen fibers were found.The CD34+, CD31+, B-cell lymphoma 2±, antigen Ki-67 20%+, pan-cytokeratin antibody-, Calretinin-, CD99-, Desmin-, MC-, p53-, S-100+, smooth muscle actin-, Vimentin+ and protein WT-1- were identified by immunohistochemistry.Conclusions:The solitary fibrous tumor has not specific clinical manifestations, the dignosis of which depends on the pathological features and detection of specific markers by immunohistochemistry.The tumor need to be identified with other spindle cell tumor, treated with operation and followed up after operation.