The cause of most childhood central nervous system tumors is unknown, but two established risk factors are ionizing radiation (eg, high-dose cranial irradiation) and specific genetic syndromes (eg, neurofibromatosis).
The most common central nervous system tumors in children are (in order)
MRI is the test of choice because it provides more detailed images of parenchymal tumors and can detect tumors within the posterior fossa, subarachnoid spaces, and the arachnoid and pia mater. CT may be done but is less sensitive and less specific.
Biopsy may be done to confirm the diagnosis and to determine tumor type and grade.
Once the diagnosis is made, staging, grading, and risk assessment are determined. Staging includes an MRI of the entire spine, a lumbar puncture for cerebrospinal fluid cytology, and a postoperative MRI to assess for any residual tumor. The World Health Organization (WHO) has created a commonly used grading system. Risk assessment is based on age, degree of residual tumor, and evidence of spread of disease.
After tumor removal, radiation therapy, chemotherapy, or both are usually required.
Entry into a clinical trial should be considered for all children with a brain tumor. Optimal treatment requires a multidisciplinary team of pediatric oncologists, pediatric neuro-oncologists, pediatric neurosurgeons, neuropathologists, neuroradiologists, and radiation oncologists who have experience treating brain tumors in children. Because radiation therapy for brain tumors is technically demanding, children should be sent to centers that have experience in this area if possible.