The patient was a 20-year-old female who visited the Department of Dentistry and Oral Surgery of Hakodate Goryokaku Hospital complaining of slight pain in the bilateral upper molar regions.
Radiographic examination showed radiopaque shadows at the bottom of the bilateral maxillary sinuses. The sinuses were surgically enucleated under a clinical diagnosis of osteoma. The lesions had the consistency and appearance of bone.
Microscopic examination revealed lamellar bone with fatty marrow containing a slight infiltration of inflammatory cells. There were few osteoblasts or osteoclasts in this lesion. Near the cut surface, cystic formation characterized by an antral mucous membrane and mucus in the cystic cavity was observed. Due to a previous history of nasal bone fracture. these findings suggested that hone fragments formed an exostosis for reactive bone proliferation.
