PAX8 Expression Variability in Cerebellar Hemangioblastoma: Case Series and Review of the Literature.

Hemangioblastomas are benign tumors of undetermined origin, and account for up to 2.5% of all intracranial tumors. They may occur either sporadically or as a manifestation of von Hippel-Lindau (VHL) syndrome. Central nervous system (CNS) hemangioblastomas are pathologically diagnosed by gross and microscopic morphology, with further support of the diagnosis conferred by a characteristic immunohistochemistry profile including PAX8 negativity. Although renal hemangioblastomas have previously been reported to be PAX8 positive, CNS hemangioblastoma positive PAX8 expression has never been reported. We reviewed 11 cases of cerebellar hemangioblastoma from our institution over a 7-year period (2010 to 2017). Tissue was stained for PAX8 to determine immunohistochemical labeling. Of 11 reviewed cases of cerebellar hemangioblastoma, 7 exhibited PAX8 immunohistochemical expression. A review of the literature found no previously reported cases of positive PAX8 labeling in cerebellar hemangiomas. PAX8 negativity is not as specific for cerebellar hemangioblastoma as previously thought, and caution must be used when relying solely on a panel of PAX2, PAX8, and inhibin A for pathologic diagnosis.