Osteosarcoma (OS) is the most common primary malignancy of bone, with a reported incidence of 1:100,000 per year.1 These tumors typically originate in the extremities and the pelvis, with only 2.7–6.6% of OSs were located in the jaws.2,3 Although conventional OS arises intramedullary, some OSs occur on the outer surface of bone, this is called surface or juxtacortical OS and exhibits distinct radiographic, histologic features and biological behavior that is obviously different from conventional OS. OSs arising on the surface of bone can be classified into three types according to the nature of the tumor: parosteal, periosteal, and high-grade surface OS.4 Parosteal OS is a low-grade OS, with an incidence of about 4% of all OSs. Periosteal OS is an intermediate-grade chondroblastic OS, accounting for less than 2% of all OSs. High-grade surface OS is the most rare subtype, accounting for less than 1%. Periosteal type tends to have a better prognosis than that of conventional OS or high-grade surface OS, but poorer than that of parosteal OS and it is capable of local recurrence and distant metastasis.5 Periosteal OS occurs extremely rarely in the jaws. To our knowledge, including this report, only ten cases have been reported. We report a case of periosteal OS located at the mental region of the mandible and review the literature with respect to clinical, radiological and histopathological criteria, we also discuss the differential diagnosis.
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