A primary neoplasm arising in the central nervous system (CNS)
- Most common solid neoplasm of childhood (second to leukemia in overall incidence)
- Most common cause of cancer death in children 0 to 14 years
- Slight male predominance
- Majority arise infratentorially (within cerebellum or brainstem) in children 1 to 14 years of age.
- Majority arise supratentorially in children <1 year of age.
- Incidence >3,000 new cases/year
- 5.4 cases/100,000 children/year (age-adjusted incidence rate, ages 0 to 19 years, between 2007 and 2011)
- Peak incidence in children ≤7 years of age
- Approximately 1 in 2,000 children born 2009 to 2011 will be diagnosed with a primary malignant CNS tumor by age 14 years.
- Brain tumors are not inherited.
- About 5% of primary brain tumors may be linked to hereditary genetic syndromes:
- Neurofibromatosis with optic pathway gliomas (NF1) and meningiomas, vestibular schwannomas (NF2)
- Tuberous sclerosis with gliomas and rarely ependymomas
- Li-Fraumeni syndrome with astrocytomas
- von Hippel-Lindau with cerebellar hemangioblastoma
- Turcot syndrome with medulloblastoma
Tumors are now classified based on histology and molecular genetic features. The most common are the following:
- Diffuse gliomas/other astrocytic tumors
- Arises from glial cells (e.g., astrocytes most common in children)
- ~50% of childhood CNS tumors
- Ranges from low-grade (grade I to II; often in the cerebellum or optic pathway) to high-grade (grade III to IV; in the cerebrum or brainstem)
- Locally recurrent and invasive when high grade
- Molecular alterations distinguish pediatric from adult gliomas.
- Embryonal tumors
- Heterogenous group of tumors that arise from malignant embryonic cells
- Comprises ~15% of childhood CNS tumors
- Most common malignant brain tumor in children
- Most common embryonal tumor (60%) is medulloblastoma (cerebellum).
- Predisposition for leptomeningeal dissemination
- Arises from ependymal cells that line the ventricular system
- 5–8% of childhood CNS tumors
- Most commonly occurs in the 4th ventricle; may arise in the spinal cord
- Locally recurrent and invasive; spinal metastases rare at initial diagnosis
- Germ cell tumors
- Derived from totipotent germ cells
- 3–5% of childhood CNS tumors
- Majority are located in the pineal or suprasellar region.
- Atypical teratoid/rhabdoid tumor
- Now classified under embryonal tumors
- <3% of childhood CNS tumors
- Majority arise in children <5 years of age.
- Propensity to arise in the posterior fossa with frequent leptomeningeal dissemination; reported in association with malignant rhabdoid tumors of the kidney
- Neuronal and mixed neuronal-glial tumors: 6% of childhood CNS tumors
- Craniopharyngioma: 3–5% of childhood CNS tumors
- Choroid plexus tumors (papilloma and carcinoma)
- Meningioma and hemangioblastoma, rare in children
- No specific causative agents are known, but there is an association with exposure to ionizing radiation, other malignancies, familial/heritable diseases, immunosuppression/immunodeficiency (CNS lymphoma).
- Molecular markers and variants of individual tumor types are being identified.
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