PIK3CA and meningioma: Mutually exclusive somatic pathogenic variants have additionally been identified in AKT3 [19], phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), the catalytic subunit alpha (PI3KCA) and regulatory subunit alpha (PI3KR1) have also been identified in meningiomas with WHO grade I meningothelial or transitional histology arising from the medial skull base [19, 22].