Genetic landscape of meningioma

Meningioma is the most common intracranial tumor, arising from arachnoid cells of the meninges. Monosomy 22 and inactivating mutations of NF2 are well-known genetic alterations of meningiomas. More recently, mutations in TRAF7, AKT1, KLF4, SMO, and PIK3CA were identified by next-generation sequencing. We here reviewed 553 meningiomas for the mutational patterns of the six genes. NF2 aberration was observed in 55 % of meningiomas. Mutations of TRAF7, AKT1, KLF4, PIK3CA, and SMO were identified in 20, 9, 9, 4.5, and 3 % of cases, respectively. Altogether, 80 % of cases harbored at least one of the genetic alterations in these genes. NF2 alterations and mutations of the other genes were mutually exclusive with a few exceptions. Clinicopathologically, tumors with mutations in TRAF7/AKT1 and SMO shared specific features: they were located in the anterior fossa, median middle fossa, or anterior calvarium, and most of them were meningothelial or transitional meningiomas. TRAF7/KLF4 type meningiomas showed different characteristics in that they occurred in the lateral middle fossa and median posterior fossa as well as anterior fossa and median middle fossa, and contained a secretory meningioma component. We also discuss the mutational hotspots of these genes and other genetic/cytogenetic alterations contributing to tumorigenesis or progression of meningiomas.