A case of peripheral osteoma occurred in the ascending ramus to just below in a 26-year-old man is presented. The patient noticed a painless swelling mass in the right side of buccal region followed by contusion in the age of 14. The localized hard mass had been growing gradually, and showed no symptoms except for facial asymmetry. Radiographic examination revealed a pigeon egg-sized, rounded, dense and radiopaque mass which protruded from the lateral surface of the mandibular ramus. Histopathological examination showed a finding of compact osteoma characterized by a dense lamellar bone mass with few stroma.
