Which pediatric brain tumor is commonly associated with visual loss and proptosis, especially in the setting of neurofibromatosis type 1?

• A. Pilocytic astrocytoma
• B. Optic pathway glioma
• C. Medulloblastoma
• D. Ependymoma

Answer: (B)

In neurofibromatosis type 1, optic pathway glioma is the tumor most commonly linked to visual loss and proptosis in children. This tumor grows along the pathways of the optic nerve, optic chiasm, or nearby hypothalamic region, directly affecting vision and sometimes causing the eye to protrude as it enlarges. The underlying cause is the NF1 mutation promoting glial cell growth along the optic pathway, leading to gradual decline in visual function and, with expansion, proptosis. While pilocytic astrocytoma is a common pediatric brain tumor, its association with NF1 is not as characteristic as that of optic pathway glioma; other tumors like medulloblastoma and ependymoma produce symptoms driven by posterior fossa involvement or hydrocephalus rather than primary visual symptoms. Imaging typically shows thickening or enhancement of the optic nerve/chiasm on MRI, reflecting the location and nature of the lesion.