Gnathic osteosarcomas: Review of literature and report of two cases in maxilla

Primary neoplasms of the skeleton are rare, accounting for 0.2% of overall human tumor burden. Osteosarcoma (OS) accounts for 15-35% of all primary bone tumors, while gnathic osteosarcomas (GOS) represent 4-8% of all osteosarcomas. GOS shows a predilection for men, a peak incidence of 33 years, and affects the mandible more than the maxilla. We review the scientific literature for a better understanding of the clinical, radiographic, and histopathological features of GOS, along with its etiology, staging, treatment protocol, prognosis, and survival. Evidence from molecular research suggests that it is a differentiation disease that disrupts osteoblasts differentiation from mesenchymal stem cells. The classical radiographic finding of a "sunburst" appearance is appreciated only in 50% of GOS. The universally accepted staging system is not commonly used due to the rarity with which they metastasize to the regional lymph nodes. A number of distinct histopathological subtypes have been described, of which osteoblastic GOS are most common. The treatment protocol is multimodal consisting of preoperative chemotherapy followed by surgery and postoperative chemotherapy, and has a 60-70% five-year survival rate. We present two case reports of osteosarcoma involving the maxillary that were initially misdiagnosed as peripheral giant cell granuloma and osteoma of the maxilla, respectively. These case reports demonstrate the diverse clinical, radiographic, and histopathological features that can be encountered in GOS.