A simple bone cyst associated with a fibro-osseous lesion in the mandible

A simple bone cyst associated with a fibro-osseous lesion in the mandible of a 12-year-old girl is reported. All teeth from the central incisor to first premolar on the left side of the mandible, were vital, and none were mobile. There was no cortical expansion. Radiological examination revealed a cyst-like radiolucent area in near the incisors and premolars in the left side of the mandible. This radiolucent area was the size of a thumb tip. Biopsy of the lesion showed blood and a thin membrane. The clinical diagnosis was simple bone cyst. Under general anesthesia, the patient underwent extirpation. In the bone cavity, a tumor was found, and histopathologically, irregular bone trabeculae and fibrous connective tissue were noted. A simple bone cyst associated with a fibro-osseous lesion of the jawbone is not common. Clinical and histopathological examinations suggested this diagnosis in our patient.