Osteosarcoma of the Mandible Arising in Fibrous Dysplasia – A Case Report

Abstract Fibrous dysplasia (FD) is a benign fibro-osseous lesion that typically behaves as a painless, slowly expanding tumor. On rare occasion, however, FD will undergo malignant transformation. When sarcomatous change occurs, osteosarcoma is the typical variant, followed by chondrosarcoma and fibrosarcoma. The incidence of malignant change varies from 1-4%, depending on whether the disease is either mono or polyostotic/syndromic (McCune Albright Syndrome, Jaffe-Lichtenstein). Despite the low incidence of malignant change, the potential lethality of this disease behooves treating surgeons to be keenly aware of the signs and symptoms indicative of malignancy. In this case report, we document a case of spontaneous transformation of FD into osteosarcoma in the setting of long-standing craniomaxillofacial FD in a 39 year-old woman.