FGFR2 and oligodendroglioma: The PLNTY is characterized by alterations of the mitogen-activated protein kinase-pathway (MAPK pathway) such as a mutation of the gene for the rapid accelerated fibrosarcoma oncogene type B at position 600 (BRAF V600E) or even a gene fusion involving the gene for the fibroblast growth factor receptor 2 or 3 (FGFR2 or FGFR3) in combination with typical histological features, such as oligodendroglioma-like areas, a diffuse growth pattern, as well as the expression of cluster of differentiation 34 (CD34) and oligodendrocyte transcription factor 2 (OLIG2) [50–53].