Knee Deep in the Nerve

A 62-year-old man presented with a 3-week history of a progressive right vision loss. His right optic disk showed some mild elevation. Automated perimetry revealed a junctional scotoma. Magnetic resonance imaging of the brain showed enlargment and enhancement of the right optic nerve, chiasm, and proximal optic tract. A chiasmal biopsy revealed a lesion consistent with malignant optic glioma of adulthood.