OLIG2 and neoplasm: Both histological classification and tumor grading were achieved using techniques such as light microscopy of hematoxylin and eosin-stained tumor sections and immunohistochemistry with different markers of lineage, proliferation, and differentiation, such as glial fibrillary acidic protein (GFAP), oligodendrocyte lineage transcription factor 2 (OLIG2), Ki67, and cytokeratin [12,14].