Sphenoid Wing Meningioma with Extraocular Muscle Involvement Mimicking Idiopathic Orbital Inflammation.

Meningiomas are slow growing, typically benign, tumors originating from arachnoid cap cells. Specifically, sphenoid wing or spheno-orbital meningiomas infiltrate the lesser wing of the sphenoid, lateral orbital wall, and orbital roof with occasional extension to the superior orbital fissure, optic canal, anterior clinoid process, and middle cranial fossa where neurologic and ophthalmologic functions are impaired by compressive injury. The extraocular muscles are rarely involved. The authors present a rare case of an spheno-orbital meningioma causing extraocular muscle enlargement mimicking idiopathic orbital inflammation and highlight important diagnostic clues to meningioma.