Low-grade osteosarcoma is predominant in gnathic osteosarcomas: A report of seven cases of osteosarcoma of the jaw.

The surprisingly high incidence (60%, 3/5 cases) of low-grade osteosarcoma explains the reason why gnathic osteosarcomas present a more favorable prognosis than osteosarcomas arising in long bones. Furthermore, it provides insight into the tumorigenesis mechanism of low-grade osteosarcomas arising in the jaw and other sites.