Optic Pathway Gliomas
Optic pathway gliomas (OPGs) comprise a spectrum of neoplasms ranging from tubular thickening of the optic nerves to massive exophytic lesions diffusely involving the chiasm and/or hypothalamus, extending from the third ventricle to the prepontine cistern. OPGs constitute approximately 5% of pediatric brain tumors. The most common presentation in children is visual disturbances, but children can also present with neuroendocrinologic disturbances and, in children under the age of 1 year, diencephalic syndrome. Children affected by the genetic condition of neurofibromatosis 1 (NF1) have a predisposition to develop OPGs with up to 15% of patients with NF1 having the diagnosis of OPG. OPG in patients with NF1 may have a better prognosis than sporadic tumors.
There is a role for observation in the management of these tumors in patients without clinical or radiologic progression. Chemotherapy is often a first-line treatment in OPGs. The role of surgery includes diagnosis in select cases with atypical appearance, subtotal resection for decompression of the visual apparatus, and salvage therapy. Gross total resection is limited to unilateral intraorbital tumors; it is rarely if ever the goal of intracranial OPGs, since there is an unresectable intrinsic component of the tumor. Radiation can be considered in children with progressive disease after chemotherapy and in children older than 3 years. With multidisciplinary treatment most children will achieve a prolonged progression-free survival; however, subsequent tumor growth can result in complete loss of vision, additional endocrine deficiencies, neurologic deficits, and poor quality of life. Better strategies to identify tumors with high risk of progression and novel therapeutic targets are needed.
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