ABSTRACT
Primary brain tumors have specific age predilection, with most adult tumors arising within the cerebral hemispheres, whereas in childhood the majority occur within the posterior cranial fossa. Primitive neuro-ectodermal tumors (PNETs), pilocytic astrocytomas, craniopharyngiomas and optic nerve gliomas occur most frequently in childhood, intracranial germ cell tumors present in the teens and early twenties while the incidence of most glial and meningeal tumors is highest in adults and increases with age. Gliomas constitute the largest histological group of primary brain tumors.
