235 Renal Hemangioblastoma in a Patient with Von Hippel-Lindau Syndrome: A Rare Tumor in an Uncommon Site

Introduction/Objective Hemangioblastomas are rare, benign, and highly vascularized tumors classified as WHO grade I, most commonly arising within the central nervous system. They typically occur in the cerebellum, followed by the spinal cord and brainstem. These tumors may present sporadically or in association with von Hippel-Lindau (VHL) disease, a hereditary condition that predisposes individuals to a variety of neoplasms. Clinical manifestations of hemangioblastomas depend largely on their anatomical location. We report a case of hemangioblastoma occurring in an exceptionally rare site. By presenting this case, we aim to contribute to the existing literature and increase awareness of this unusual tumor presentation. Methods/Case Report A 24-year-old female with a known history of von Hippel-Lindau (VHL) syndrome and a previously diagnosed spinal hemangioblastoma presented with a growing renal mass initially suspected to be renal cell carcinoma. Imaging demonstrated an increase in mass size from 2.0 × 1.9 cm on prior studies to 3.7 × 3.0 cm at the time of presentation. The patient subsequently underwent a partial nephrectomy for definitive diagnosis and management. Histological examination of the resected renal lesion revealed sheets of mildly atypical round to ovoid cells within a complex capillary network. Some tumor cells showed abundant microvacuolated clear cytoplasm, and large areas of hemorrhage and vascular congestion were observed. Immunohistochemical staining showed strong positivity for Inhibin, Pax8, S100, NSE, CD10, CD31, and SMA, with focal positivity for CK AE1/AE3 and negativity for HMB45. Positive controls were appropriately reactive. The overall histopathologic and immunophenotypic findings supported a diagnosis of renal hemangioblastoma. This case adds to the limited literature on renal hemangioblastomas, particularly in the setting of VHL syndrome, where renal involvement is more commonly associated with clear cell renal cell carcinoma. Results NA Conclusion Hemangioblastoma of the kidney is an exceedingly rare benign neoplasm, with fewer than 20 cases described in the English literature. Unlike the typical association of von Hippel-Lindau (VHL) syndrome with clear cell renal carcinoma and central nervous system hemangioblastomas, most renal hemangioblastomas occur sporadically and are not linked to VHL disease. Recognition of this rare entity is essential to avoid misdiagnosis, particularly in patients without other features of VHL syndrome.