CYSTIC OPTIC-NERVE MENINGIOMA PRESENTING WITH ACUTE PROPTOSIS

A 37-year-old woman presented with acute left-sided proptosis. Magneti c resonance imaging demonstrated a solid intraconal mass lesion with a n associated 'capping' cyst. This lesion was resected and found on his tological examination to be an optic nerve sheath meningioma. Small pe rineural cysts have been reported with optic nerve sheath meningioma b ut we believe this to be the ;first reported case of a large peritumor al cyst associated ,vith this type of mass lesion. We speculate on the aetiology of the cyst and the associated acute proptosis.