Fibrous dysplasia of the zygomatic bone and mandibular coronoid process: A case report

Fibrous dysplasia (FD) is a benign bone disease characterized by the replacement of normal bone with fibroosseous connective tissue. Although FD may occur in the facial bones, it rarely occurs in both the zygomatic bone and mandible simultaneously. We herein describe a 59-year-old woman who developed FD in the zygomatic bone and mandibular coronoid process. She was referred to our hospital because of the presence of a radiopaque area around the maxillary tuberosity. Computed tomography showed a bell-shaped, radiopaque mass in the right zygomatic bone and upward extension of the right coronoid process. Although we biopsied the lesion of the zygomatic bone, we could not precisely diagnose the lesion. The lesion was excised intraorally under general anesthesia. Histological examination revealed FD in the zygomatic bone and coronoid process. Postoperative computed tomography showed a residual lesion in the zygomatic bone, but there was no enlargement even 1 year postoperatively.