CDKN2A and meningioma: A second bifrontal craniotomy was performed to resect the recurrent meningioma and pathology revealed a WHO-3 meningioma based on mitotic activity and homozygous deletion of CDKN2A detected by Oncomine sequencing, which also revealed a pathogenic NF2 c.557+2T>G splice mutation (thus indicating secondary progression from a WHO-1 tumor).