OLIG2 and ependymoma: With the exception of supratentorial ZFTA fusion-positive ependymomas which can show patchy Olig2 positivity, extensive Olig2 and patchy GFAP positivity are otherwise atypical in ependymomas [19] and should prompt further consideration for an alternative diagnosis such as CNS tumors with BCOR/BCOR(L1) fusion, as substantiated in our case.