It is a glioneuronal neoplasm in the cerebral cortex of children or young adults defined by the presence of a pathognomonic glioneuronal element that may be linked to glial nodules and activating mutations of fibroblast growth factor receptor 1 (FGFR1) (CNS WHO grade 1 according to WHO classification of CNS and pituitary tumors, 2021 ). The gene discussed is FGFR1; the disease is pituitary tumor.