OLIG2 and ependymoma: Subsequent studies have confirmed that these tumors are characterized by peculiar histopathological and immunohistochemical features, including circumscribed growth, ependymoma-like perivascular pseudorosettes, delicate branching capillaries, microcystic pattern, focal or absent GFAP immunostaining, focal OLIG2 positivity, variable expression of NeuN, and immunoreactivity for BCOR [1, 3, 17].