Abstract: Objective To analyze the clinical manifestations, surgical options and prognosis of primary solitary fibrous tumors (SFTs) of orbit. Design Retrospective cases series. Participants 38 cases of primary orbital SFTs confirmed by pathology from 2017 to 2022 in Beijing Tongren Hospital. Methods The course of the disease, symptoms, signs, imaging and histopathology, as well as follow-up and survival data were analyzed. And recurrence free survival (RFS) and overall survival (OS) were analyzed by Kaplan-Meier curve. Main Outcome Measures Visual acuity, clinical symptoms and signs, pathological features, recurrence, and survival. Results The median age of initial cases and recurrent cases was 37 years (5~65 years) and 64.5 years (41~81 years), respectively (P=0.000). The sensitivity of preoperative imaging examination for SFTs was 22.58%, and the misdiagnosis rate was 41.93%. Pathological examination showed that 97.37% of all SFTs tumors were CD34 positive, and all tumors were STAT6 positive (100%). The mean course of disease of 37 patients with follow-up data was 8.6±7.6 years (1.9~31.0 years), and the mean course of disease of 16 patients with recurrence was 15.1±7.8 years (3.9~31.0 years). The mean interval between the first operation and the last operation was 12.7±7.9 years (1.3~29.7 years). The 36 patients with survival data (excluding biopsy and one case of lost follow-up) had 91.67% OS and RFS after surgery (first operation for primary cases, last operation for recurrent cases), and the mean follow-up time was 2.3±1.4 years (0.1~5.8 years) and 2.4±1.9 years (0.0~5.8 years), respectively. Of the 10 cases of malignant SFTs, 4 cases received postoperative radiotherapy and no recurrence was reported. 6 cases did not receive radiotherapy, of which 1 case relapsed and died, and 5 cases had no relapse at present. 3 cases recurred, of which 1 was malignant and 2 benign. Three cases died, of which two were tumor-related. Conclusion Most primary cases of orbital SFTs occur in young adults. Both benign and malignant orbital SFTs can recurs and spread to the intracranial easily. Extensive intracranial spread of benign SFTs can also lead to death. Imaging examination may misdiagnose SFTs as other tumors. (Ophthalmol CHN, 2023, 32: 208-214)

Key words: solitary fibrous tumor, clinicopathologic features