Optic nerve meningeal hemangiopericytoma: a clinicopathologic case report.

A 36-year-old woman presented with progressive loss of vision in the left eye for 3 years, and rapid progression and painful protrusion of the eye for one month. Clinical evaluation revealed no light perception, severe proptosis and hypoglobus, optic atrophy, and optociliary shunt vessels. Orbital imaging showed a well-defined heterogeneous intraconal mass partially encasing the optic nerve. A clinical diagnosis of optic nerve sheath meningioma was made, and the tumor was completely excised along with enucleation, followed by postoperative adjuvant external beam radiotherapy. There was no local recurrence at 15 month follow-up. Histopathologically, the tumor was found to be arising from the optic nerve meninges with classical "stag-horn" pattern and abundant cellularity. Immunohistochemistry supported the histopathological diagnosis of hemangiopericytoma. Optic nerve meningeal hemangiopericytoma is extremely rare-only two such cases have been reported in the literature.