Arachnoid cyst of the optic nerve: a case report.

BACKGROUND

To report a case of an arachnoid cyst of the optic nerve with homonymous optic atrophy.

HISTORY AND SIGNS: A 17-year-old female patient presented with severe visual loss, limited to light perception, of the left eye. She underwent complete ophthalmologic examination, color fundus photography and electrophysiological study. Magnetic resonance imaging (MRI) revealed the presence of a fusiform structure involving the left optic nerve from the orbital apex to the posterior surface of the globe. The clinical and radiographic features are consistent with an arachnoid cyst of the optic nerve.

THERAPY AND OUTCOME: The patient refused to be treated. Two years later, the VA remained unchanged.

CONCLUSIONS

The arachnoid cyst of the optic nerve is a rare entity. Its differential diagnosis from the primary optic nerve glioma is difficult and important to be made in order to be treated properly.