Caught by a masquerade: sclerosing orbital inflammation.

Idiopathic sclerosing inflammation of the orbit is a distinct form of orbital inflammatory disease characterized by slow and relentless involvement of orbital structures. It is this insidious and relentless course that makes distinction from neoplastic lesions clinically difficult. We report the case of a patient with a several-week history of headache and decreased vision that was originally thought to represent an optic nerve sheath meningioma, based on clinical and radiographic evaluation. Subsequent histopathology from an optic nerve biopsy, however, was more consistent with optic nerve glioma. Eventually, pathologic examination of whole sections through the optic nerve was required to establish and confirm the actual diagnosis of sclerosing orbital inflammation.