Teaching Case

The patient consulted for a left mandibular mass that had appeared two months previously. It increased in size, even after teeth extraction and antibiotic therapy. Clinical examination revealed a mass involving the whole left mandibular region, extending from the zygoma to the temporo-mandibular joint, and including the parotid and sublingual spaces. There was no obvious lymphadenopathy. CT scan and MRI were performed.

A 32-year-old man consulted for a left mandibular mass that had appeared two months previously. It increased in size, even after teeth extraction and antibiotic therapy. Clinical examination revealed a mass involving the whole left mandibular region, extending from the zygoma to the temporo-mandibular joint, and including the parotid and sublingual spaces. There was no obvious lymphadenopathy. CT scan and MRI were performed. Imaging findings were strongly suggestive of an osteosarcoma, which was confirmed by histology

Osteosarcoma is a highly malignant neoplasm that occurs most often in children and adolescents (75 percent of patients are between 10 and 25). With the exception of multiple myeloma, it is the most frequently occurring primary bone tumor. Most osteosarcomas arise in the long bones of legs and arms, particularly around the knee. Only about 7 percent of osteosarcomas arise in the jaws. Maxillar lesions arise from the sinus and alveoli, whereas mandibular lesions occur in the body and ramus of the mandible. The mean age of these patients is about two decades older than that of patients with osteosarcoma of the long bones. Symptoms depend on the location of the tumor. Mandibular tumors frequently cause a focal painful swelling, while, conversely, maxillary lesions usually produce no pain. The common lesions of the masticator space are inflammatory (odontogenic abscess) or tumoral (sarcoma, non-Hodgkin lymphoma, malignant Schwannoma or infiltrating squamous cell carcinoma) in origin. As presented, the new bone formation with perpendicular speculated pattern from the mandibular bone is typical of an osteosarcoma. Preoperative evaluation by CT scan and MRI is useful for treatment planning. CT provides excellent detection of tumor calcification, ossification and cortical involvement. MRI is more effective in demonstrating the intramedullary and extraosseus tumor components on both T1- and T2-weighted images.