Osteosarcoma of the Mandible Arising in Fibrous Dysplasia

A Grade 3 chondroblastic osteosarcoma is reported in the mandible of a 37-year-old man with longstanding polyostotic fibrous dysplasia. There was also a history of multiple endocrine disturbances including hyperthyroidism, pituitary adenoma, and acromegaly. Malignant transformation of fibrous dysplasia is very rare and occurs most often when the lesion is polyostotic in distribution. The patient received preoperative radiation therapy followed immediately by marginal excision, i.e., left hemimandibulectomy. Forty-two months after initial presentation of the osteosarcoma of the mandible, he is alive with no evidence of disease.