Brain tumors are the most common form of solid cancer in the pediatric population/childhood. Their incidence has increased within the past few decades, with a current annual age-adjusted rate of 3.2 cases per 100,000 children, as reported by the Cancer Statistics Report (CSR).

Pediatric brain tumors are primary classified by their location within the intracranial compartments in infratentorial and supratentorial tumors . About 60 % of brain tumors in children occur in the infratentorial compartment, and they may be intrinsic to the brain stem (Fig. 22.3) or located with the cerebellar parenchyma or cerebrospinal fluid spaces of the posterior fossa (Fig. 22.4). Supratentorial tumors are usually hemispheric (Fig. 22.5) but may also arise from the suprasellar and/or pineal region (Fig. 22.6). For the youngest children, the ratio of infratentorial versus supratentorial lesions is reversed, and in the first year of life, supratentorial tumors are actually slightly more prevalent.

The World Health Organization (WHO) outlines another important classification. This is based upon a tumor’s behavior and its histopathological characteristics. Inside the infratentorial compartment, the most typical histological subtypes are cerebellar astrocytomas, medulloblastomas, ependymomas (Figs. 22.7 and 22.8), and brain stem gliomas. In the supratentorial space, gliomas and particularly low-grade astrocytomas (Fig. 22.9) remain the most common tumors of the cerebral hemispheres. Craniopharyngiomas (Fig. 22.10) and optic pathway gliomas of the suprasellar region and germ cell tumors of the pineal region are also fairly common.