Vasoproliferative Retinal Tumor with Hemangioblastoma-like Features: Evaluation with von Wilebrand Factor.

Objectives: To investigate the clinicopathologic characteristics and molecular biomarkers of atypical vasoproliferative retinal tumor (VPRT) with hemangioblastoma-like histopathologic features and concomitant von Willebrand factor (VWF) abnormalities. Methods: A 48-year-old woman undergoing phacoemulsification and 25-gauge pars plana vitrectomy with tumor resection was evaluated. Histopathological findings and immunohistochemical study of the resected tumor were performed using CD34, α-smooth muscle actin (αSMA), and glial fibrillary acidic protein (GFAP) markers. Preoperative plasma and intraoperative vitreous fluid VWF antigen levels, as well as ristocetin cofactor activity, were quantified using latex immunoturbidimetry. Results: Ultra-widefield imaging and angiography demonstrated a peripheral retinal tumor with intense vascular leakage and surrounding capillary nonperfusion. Histopathology showed hyalinized vascular components supportive of VPRT, along with abundant CD34/α-SMA-positive microvessels and scant GFAP-positive glial cells. Notably, numerous foamy vacuolated poorly differentiated cells suggested mixed hemangioblastoma-like features. Preoperative plasma VWF antigen (182.6%) and ristocetin cofactor activity (147.7%) were elevated, and vitreous VWF antigen was successfully detected at a low but distinct level (7.7%).and suggests that VWF abnormalities in the plasma and vitreous may reflect endothelial activation and/or blood-retinal barrier disruption in a subset of vascularized retinal tumors. Conclusions: Our findings demonstrate that VPRT may exhibit mixed clinicopathologic features, including hemangioblastoma-like components, which underscores the necessity of immunohistochemical assessment for definitive diagnosis. Furthermore, the quantification of VWF abnormalities in the plasma and vitreous suggests that VWF serves as a potential biomarker reflecting endothelial activation and/or blood-retinal barrier disruption in vascularized retinal tumors.