A primary optic nerve sheath chordoid meningioma.

Primary optic nerve sheath meningiomas (ONM) are rare. Most of these are World Health Organization Grade I meningiomas. Because of the intimate relationship to the optic nerve sheath from which they arise, radical excision is often not feasible. The chordoid variant of meningioma is an infrequent tumor and extremely uncommon among primary ONMs. We report a 36-year-old woman with painless proptosis and normal visual acuity who presented to us with an exophytic intraconal mass, which was excised. Histology revealed a chordoid meningioma. We could find only two previous reports, which are discussed.