A case of osteoblastoma arising in the mandible

Osteoblastoma is a rare tumor that accounts for less than 1% of all bone tumors and is characterized by the development of osteoblasts and osteoid tissue. It is classified as an intermediate type tumor with local aggressiveness. The tumor mass is usually larger than 2 cm, and there have been no reports of large osteoblastomas in Japan in recent years. We report the case of a large osteoblastoma, including a description of the previously obtained X-ray films. The patient was a 22-year-old man who visited our hospital with a chief complaint of swelling of the left side of the mandible. The tumor measured 40×40× 30 mm, and X-ray films showed a radiolucent image including a calcified body with a clear margin. Osteoblastoma was diagnosed on the basis of two biopsies. Segmental mandibulectomy was performed with the patient under general anesthesia. There has been no recurrence after the operation, and the patient is making good progress. A panoramic X-ray film taken 7 years ago (at 15 years of age) revealed slight bone resorption resembling periodontitis in the region where the tumor had developed. Consequently, there was a high probability that this X-ray film indicated an early stage of this tumor.