Fibrous dysplasia masquerading as chronic maxillary sinusitis.

Fibrous dysplasia is a rare disease of unknown cause that affects one or multiple bones. In its monostotic form, only one bone is involved. The maxilla is the most commonly affected facial bone. Facial deformity with or without pain is the most common presentation of fibrous dysplasia affecting the craniofacial bones. In certain cases the disorder can present clinically as chronic maxillary sinusitis. The clinical, radiologic, and histologic findings, as well as the differential diagnosis and treatment of this condition are reviewed.