Orbital neurilemoma with extension through the superior orbital fissure

An otherwise healthy 33-year-old man developed slowly progressive unilateral proptosis. Computed tomography demonstrated a large orbital mass extending posteriorly through the superior orbital fissure. The encapsulated tumor, including the portion within the superior orbital fissure, was completely removed by a lateral orbitotomy. Histopathologic examination revealed a neurilemoma (schwannoma). In spite of extension of the tumor through the superior orbital fissure, the patient had excellent vision and no motility disturbance before or after surgery. The clinical, computed tomographic, histopathologic, and ultrastructural features of this orbital tumor are discussed.