Optic nerve glioma and optic neuritis mimicking one another: case report

The clinical and radiographic presentations of optic nerve gliomas and optic neuritis are for the most part distinct and their diagnoses straightforward. We present two cases illustrating the occasional difficulty one can encounter in distinguishing neoplastic from inflammatory optic neuropathies.

Patient 1 is a 17-year-old girl who presented with acute onset of pain and rapidly progressive visual loss in the right eye. Patient 2 is a 38-year-old man who presented with painless progressive visual loss in the left eye.

Patient 1 was initially diagnosed with idiopathic retrobulbar optic neuritis. Interval increase of the optic nerve on magnetic resonance imaging prompted a biopsy of the optic nerve, which revealed a pilocytic astrocytoma. Patient 2 was found to have left optic nerve enhancement most consistent with an optic nerve glioma. Before a biopsy, the patient spontaneously improved without treatment, indicating an inflammatory process.

Differentiating between optic nerve neoplasm and inflammation may be difficult. On occasion, the classic clinical finding of pain with eye movement and the radiographic finding of enlargement and enhancement of the optic nerve may be misleading. Open biopsy of the optic nerve is indicated only after a completely negative metabolic, infectious, and inflammatory workup; interval increase of the optic nerve on magnetic resonance imaging; and failure of the patient to recover vision.