A rare mandibular osteosarcoma case of Li-Franmeni syndrome with a germline p53R273H mutation

Li-Fraumeni syndrome (LFS) is a rare hereditary disorder with a predisposition to malignant tumors. Osteosarcoma is a common malignancy of LFS patients but infrequently arises in jaw. Oral and maxillofacial surgeons may overlook LFS among patients with the malignancy, whereas LFS individuals require oncological surveillance and avoid radiation therapy due to the risk of radiation-induced second primary tumors. We report a 17-year-old boy who complained of a tumor at the periphery of the left mandible. The tumor exhibited a “sunburst” pattern by computed tomography (CT) and strong uptake of fluorodeoxyglucose on positron emission tomography-CT. The tumor consisted of spindle/stellate cells with nuclear atypia, conspicuous mitosis and a high ratio of Ki-67-positivity, accompanying chondroid mucinous matrix and malignant osteoid. Thus, the tumor was diagnosed osteosarcoma. As osteosarcoma primarily develops at jaw during the 3rd or 4th decade of life, the onset age of the patient was young. His grandmother and sister had developed breast cancer and malignant lymphoma, respectively, at young ages. Accumulation of p53 protein in the sarcoma cells was observed. Taken together, the patient was diagnosed with LFS. The patient, his mother, and siblings had a germline heterozygous missense mutation at codon 273 of the TP53 gene (from CGT [arginine] to CAT [histidine]). The present patient is the fourth case of mandibular osteosarcoma among the LFS population. The young age onset and a family history of early-onset malignancies help diagnose LFS in patients with this rare presentation that mandibular osteosarcoma is the first malignancy.