Multiple-site osteosarcomas of the jaw in a single patient. A true case of a metachronous lesion?

A case of multiple-site osteosarcomas in the jaw of a 56-year-old patient is reported. The disease occurred consecutively at three different sites (left maxilla, left mandible, right mandible) separated by time intervals of 12 and 18 months, respectively. Metachronous osteosarcomas of the long bones is a rare form of osteosarcoma and implies multiple lesions appearing at different times, each one behaving clinically as a primary lesion. The pathogenesis of this disease is unknown as it is unclear whether the lesions represent independent primary tumours or metastatic disease.