FGFR1 and pilocytic astrocytoma: While no specific differentiating histologic criteria have been reported, it has emerged that there are distinguishing clinicopathologic features of these tumors; subsequent larger studies have revealed that pilocytic astrocytoma with FGFR1 mutation are predominately extracerebellar and frequently midline in location, (in contrast to BRAF-fusion positive pilocytic astrocytomas, which predominate in the cerebellum) [40].