A large mass in the right orbit, causing proptosis, ptosis of the right upper eyelid, and limitation to eye movements, was surgically removed from a 51-year-old woman suffering from Paget's bone disease (PBD). Histologically, a giant cell tumor of the bone (osteoclastoma) was diagnosed. No bony involvement was apparent either operatively, microscopically, or on preoperative computed tomographic scans. The neoplasm has not recurred in a 3-year follow-up. In addition to the fact that osteoclastoma complicating PBD is rare, the extraskeletal origin of the tumor is a matter of interest and can be tentatively explained by an unusually powerful systemic stimulus acting on circulating osteoclast precursors. HUM PATHOL 31:1527-1531.
Copyright 2000 by W.B. Saunders Company