A 78-year-old healthy man, with a 30-year history of an increased prominence of the left eye, noted progressive proptosis of his left eye and increasing diplopia over a period of several years.
Visual acuity was 20/30 in both eyes, with decreased color vision in his left eye. An afferent pupillary defect was present in his left eye. There was a left proptosis of 9 mm with decreased retropulsion. Mild ptosis and decreased ductions in all directions were present, and the left optic disc was slightly swollen. Computed tomography revealed a circumscribed mass in the left superomedial orbit (Fig 1).
A lateral orbitotomy was performed, and a soft, purplish mass was excised. Pathological examination showed this lesion to be a hemangiopericytoma (Fig 2).
Hemangiopericytomas are vascular tumors composed of spindle-shaped or rounded cells with indistinct cell borders, proliferating around endothelium-lined capillaries. They can occur anywhere in the body and have even