OLIG2 and neoplasm: Immunohistochemically, the tumor cells were positive for S-100 protein (Figure 3C), glial fibrillary acidic protein (GFAP; Figure 3D), and epithelial membrane antigen (EMA) with dot-like positivity (Figure 3E), and negative for oligodendrocyte transcription factor 2 (Olig2; Figure 3F).