PIK3CA and meningioma: Recent next-generation sequencing has elucidated a number of recurrent genetic alterations in NF2-nonmutated meningiomas which are driven by four mutually exclusive pathways: increased hedgehog signaling (through SMO, SUFU or PRKAR1A mutations); TRAF7 (with either KLF4 mutation or PI3K pathway activation); RNA polymerase II subunit A (POLR2A) mutations; and other (i.e., AKT1) mutations (68, 78).