Optic sheath schwannomas: report of two cases.

INTRODUCTION: Schwannomas are benign tumors that arise from Schwann cells in the peripheral nervous system. The vestibular division of the VIIIth cranial nerve is the nerve segment most commonly affected, the trigeminal nerve root being the next most frequently affected. Although schwannomas of other cranial nerves are very rare, these nerves do have myelinated sheaths composed of Schwann cells and are potential sites for intracranial schwannomas. However, previous studies have suggested that the term 'schwannoma' should not be applied in the case of optic nerve pathology, although two cases of optic nerve sheath schwannoma have been reported to our knowledge.

PURPOSE: The purpose of this paper is to report two cases of the exceedingly rare entity of optic sheath schwannoma and to discuss its histopathogenesis.