PIK3CA and meningioma: For instance, an increased PD-L1 expression was found in TRAF7-mutated, compared with wild-type skull-base meningiomas [58], and an increased number of CTLA4+/CD3+ lymphocytes was found in grades 2 and 3 meningiomas harboring the PI3K–AKT–mTOR pathway or SMO mutations [59].