A pediatric brain tumor is an abnormal growth of cells in the brain of a child. Children, from infants to teenagers, can develop brain tumors. In fact, brain tumors are the most common solid tumors in children. Fortunately, they are rare. Unlike adult brain tumors, metastaic tumors that spread from a tumor elsewhere in the body are exceedingly rare in the pediatric population. Virtually all pediatric brain tumors are primary, meaning that they originate from cells that comprise the brain and its coverings. Primary brain tumors may be classified as benign or malignant. A benign tumor is one that is grows slowly and is non-invasive. A malignant tumor, rather, is rapidly growing and invades surrounding tissue.
Pediatric brain tumors most commonly occur in the posterior fossa or the rear compartment of the skull. Typical kinds of tumors in this location include medulloblastomas (also called primitive neuroectodermal tumors or PNETs), brain stem gliomas, pilocytic astrocytomas and ependymomas.
Pediatric primary brain tumors are classified into four grades established by the World Health Organization (WHO). Grade I tumors are benign and surgically curable while Grade IV tumors exhibit very aggressive behavior. A pilocytic astrocytoma is a type of tumor that is benign and surgically curable in many cases (WHO grade I). A medulloblasotma, or PNET, is a pediatric tumor that is malignant and highly invasive with a rapid rate of growth (WHO grade IV).
Many brain tumors have genetic abnormalities that alter their patterns of growth. Some genetic disorders are associated with an increased risk of brain tumor formation, such as neurofibromatosis, Von Hippel-Lindau disease, or retinoblastoma. Exposure to extremely high doses of radiation increases the risk of brain tumor formation.
Symptoms caused by a brain tumor vary with the child's age but can include enlarged head circumference, headaches, nausea and vomiting, seizures, new onset difficulty with previously acquired motor skills such as walking. Children will often come to medical attention later than adults because they may deny their symptoms and serious signs may go unrecognized. The diagnosis of a pediatric brain tumor is most commonly made with CT and/or MRI imaging of the brain.
Neurosurgeons have an important role to play in the treatment of pediatric brain tumors. Meduloblastomas are malignant tumors; however, a radical surgical resection along with radiation and chemotherapy can produce a lasting cure. Pilocytic astrocytomas, on the other hand, are benign tumors, in general, and can be cured via a gross total resection. Ependymomas are also typically benign tumors but can be very adherent to surrounding brain structures. A gross total resection can produce a lasting cure but residual tumor is often treated with chemotherapy and radiation. Pediatric brain tumors can occur in other locations besides the posterior fossa and the full complement of neurosurgical techniques and adjuvant therapy must be brought to bear.