Neurosarcoidosis mimicking a malignant optic glioma.

A 55-year-old African-American man developed progressive unilateral optic neuropathy and periocular pain. MRI showed thickening and enhancement of the mid-orbital segment of the ipsilateral optic nerve. Optic neuritis was diagnosed, and he was treated with corticosteroids without improvement. After being lost to follow-up, he returned with worsening vision in the affected eye, aggravated pain, and proptosis. MRI now showed thickening and enhancement of the entire orbital and intracranial segments of the optic nerve. Because the patient had no light perception vision in that eye and a malignant glioma was suspected, he underwent optic nerve biopsy that revealed non-caseating granulomas throughout the optic nerve tissue. CT body imaging failed to disclose other evidence of sarcoidosis. Neurosarcoidosis limited to the optic nerve is rare but should always be suspected in such circumstances. An exhaustive effort to find extracranial evidence for this diagnosis should be undertaken before resorting to optic nerve biopsy.