OLIG2 and neoplasm: Histopathological, immunohistochemical (expression of GFAP without Olig2 and SOX10) and ultrastructural findings (particularly, the presence of cilia, junctional apparatuses between the neoplastic glial cells’ intermediate filaments, and microvilli-like structures between tumor cells) [5, 9, 22] were in line with an ependymal differentiation for these tumors.