Fibrous dysplasia of the ethmoid sinus.

Although craniofacial bone is the second common site of fibrous dysplasia involvement, it is rarely found in the paranasal sinus. Among fibrous dysplasia of the head and neck, the maxilla and mandible are the most frequent sites to be involved. Fibrous dysplasia becomes dormant in adolescence and early adult life and is more common in female. It is one of the fibrous osseous lesions and should be differentiated from osteoma and ossifying fibroma. Radiographically, fibrous dysplasia showed "groundglass" bone appearance on CT scans with bone window. Histopathologically, it presents woven-type bone embedded in a cellular fibrous stroma without osteoblastic rimming. We presented a case of 25-year-old female with fibrous dysplasia in her right side ethmoid sinus. She visited to us with the chief complaint of right side headache since adolescence. The lesion was removed by endoscopic sinus surgery and pathology proved fibrous dysplasia. The patient was free of headache after operation. The advance of endoscopic sinus surgical technique, makes it an optimal method for the pathological diagnosis and treatment to avoid the cosmetic problems caused by external approach in limited paranasal sinus fibrous osseous lesions.