Abstract: Objective To describe the clinicopathological features of orbital intravascular papillary endothelial hyperplasia (IPEH). Design Retrospective case series. Participants Nine cases of orbital IPEH retrospectively reviewed in Tianjin Eye Hospital in 2006–2019. Methods The clinical and pathological features were reviewed. The clinical data were evaluated for patient age, gender, clinical history, clinical features, Grayscale and color Doppler ultrasound, CT and MRI. Main Outcome Measures Pathological data, including gross presentation, tumor size, histopathological and immunohistochemical features were also reviewed. Results The study group included 7 females and 2 males. The average age at diagnosis was 46.8±11.0 years. The duration of symptoms before seeing an ophthalmologist was less than 2 months in most cases (7/9)，and the most common symptoms were proptosis (9/9) and decreased eye motility (3/9). Grayscale and color Doppler US examinations showed an oval or round lesion with homogeneous echogenicity. No detectable vessels were found inside tumors by color Doppler US examinations. CT scanning (all 9 cases) revealed a well-circumscribed mass with homogeneous soft tissue density. Most lesions (8/9) located in retrobulbar muscle cone, however one case was extraconal. MRI (3 cases) showed isointense T1 signal and hyperintense T2 signal. The appearance of the tumor was gray-purple or gray-yellow, the capsule was intact, and there was no obvious adhesion to the surrounding tissues. The diameter of tumors was 10~20 mm. Photomicrograph showed the multiple small papillary projections lined by a single layer of plump endothelial cells and supported by fibrous connective tissue core, and multiple vascular channels. The endothelial cells were positive for CD31 and CD34. At the follow-up, 8 cases had no recurrence, and only 1 case recurred after 7 years of surgical excision. Conclusion Orbital IPEH was a very rare vascular lesion, which often occurred in the muscle cone of the adult orbit. The tumor was single, the boundary is clear, and there was little recurrence after surgical excision. (Ophthalmol CHN, 2021, 30: 51-55)

Key words: intravascular papillary endothelial hyperplasia, orbit, clinicopathological features