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Craniopharyngioma (WHO grade I) is a benign, partly cystic epithelial tumor of the sellar region presumably derived from Rathke pouch epithelium.[49] Two clinicopathological forms are distinguished: adamantinomatous and papillary. This type of tumor accounts for 1.2% to 4.6% of all brain tumors. The age incidence is bimodal; peaks are observed in children aged 5 to 14 years and in adults older than 50 years. The most common localization is suprasellar with an intrasellar component. Among these, 30% extend anteriorly, 23% extend into the middle fossa, and 20% extend into the retroclival area. In a large series, 60% to 93% of patients had a 10-year recurrence-free survival. The most significant prognostic factor associated with tumor recurrence is the extent of surgical resection; lesions larger than 5 cm carry a worse prognosis. The recurrence rate is significantly higher after incomplete resection.

(Refer to the Tumors of the Sellar Region section of this summary for treatment information. Refer to the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview for more information.)

Tumors of uncertain histogenesis

Capillary hemangioblastoma (WHO grade I) occurs sporadically and is associated with the familial tumor syndrome von Hippel-Lindau (VHL) disease.[50] VHL disease is inherited through an autosomal dominant trait and is characterized by the following: capillary hemangioblastomas of the CNS and retina, clear cell renal carcinoma, pheochromocytoma, pancreatic tumors, and inner ear tumors. The syndrome is related to germline mutations of the VHL tumor suppressor gene, which is located on chromosome 3p25-26. VHL disease is estimated to occur at rates of 1:36,000 to 1:45,500 of the world population. Capillary hemangioblastomas typically occur in adults; the mean age of patients with VHL-associated tumors is 29 years. Capillary hemangioblastomas may occur in any part of the CNS; sporadic tumors occur primarily in the cerebellum. VHL patients often have multiple capillary hemangioblastomas at various sites, including the cerebellum, brain stem, and spinal cord. Because of advances in microsurgical techniques, mortality and morbidity are low for sporadic capillary hemangioblastomas. In VHL disease, hemangioblastoma is the most common cause of death, followed by renal cell carcinoma. The median life expectancy of VHL patients has been reported to be 49 years. Periodic screening of VHL patients with magnetic resonance imaging should start in those older than 10 years.

Tumors of peripheral nerves that affect the CNS

Schwannoma (WHO grade I), also known as neurilemoma and neurinoma, is usually an encapsulated benign tumor composed of differentiated neoplastic Schwann cells.[51] This is a common tumor of the peripheral nerves that accounts for an estimated 8% of brain tumors and 29% of primary spinal tumors. Schwannomas occur frequently in patients with NF2. The peak incidence is in the fourth to sixth decades of life. Three histologic variants include cellular schwannoma, melanotic schwannoma, and plexiform schwannoma. Inactivating mutations of the NF2 gene on chromosome 22q12 have been detected in approximately 60% of schwannomas. Schwannomas are slow-growing benign tumors that only rarely undergo malignant change.