Discussion

Osteogenic sarcoma is the most common primary bone malignancy. Despite this, it remains an uncommon tumor representing approximately 0.2% of all malignancies.¹ Although usually found in the metaphyseal region of long bones, osteosarcoma has been reported rarely in the craniofacial bones. Osteosarcomas represent approximately 1% of head and neck malignancies and 6-10% of all osteosarcomas.² A specific pathogenesis of osteosarcoma has not been described; however, there are several predisposing factors, including rapid bone growth during adolescence, exposure to radiation, and bony abnormalities such as Paget disease, osteochondromatosis, and chronic osteomyelitis.^{3, 4} None of these factors applied to the patient.

Osteosarcoma can be classified by cellular differentiation as osteoblastic, fibroblastic, or chondroblastic. The chondroblastic subtype is generally composed of atypical chondroid areas comprising pleomorphic and atypical binucleate cells.⁵ In the craniofacial bones, osteoblastic osteosarcoma is the most common subtype, followed by chondroblastic.

Physical examination and radiological findings are invaluable in the diagnosis, staging, and preoperative treatment planning of patients with osteogenic sarcomas. Ultrasound and radiographs can diagnose osseous involvement, with one series reporting positive predictive values of 53.3% (24/45) and 97.8% (44/45), respectively.⁶ Radiographic findings such as a mixed radiolucent and radiopaque lesion, periodontal ligament widening, a radiopaque mass with “moth-eaten” appearance, and presence of a Codman triangle have been reported in head and neck osteosarcomas.⁷ The classic “sunburst” appearance of malignant osteoid formation in extremity osteosarcomas is also often demonstrated in head and neck osteosarcomas.⁴

CT is primarily used for staging and improving the diagnostic yield of biopsy. CT findings in the osteosarcoma of the face have been shown to differ based on the location of the mass. Sarcomas of the maxilla tend to be found on the alveolar ridge with an equal distribution of lytic and blastic osseous disease, while those found on the mandible tend to be at the ramus and/or condyle with predominately blastic disease, as was seen in our case.² CT can also improve the detection of lytic lesions that may not be readily apparent on radiography. MRI is indispensable for accurately staging osteogenic sarcomas, including evaluating for direct and perineural disease spread.⁸

The most common presentation of mandibular osteosarcoma is local swelling with or without pain or numbness, and limitation in mouth opening.^{1, 4, 9} Several less common signs include tooth loosening, weight loss, and nasal bleeding.^{4, 9} Owing to the rarity of the disease, determining a conclusive set of prognostic factors is difficult.^{4, 9} Several prognostic factors for osteogenic sarcoma have been studied, including age, sex, tumor site, radiographic appearance, histology, tumor grade, and predisposing conditions.^{4, 9} Of these factors, older patient age (> 60 y), nonmandibular location, tumor size greater than 6 cm, and a history of previous trauma were found to be statistically significant factors associated with decreased disease-free survival.^{4, 9} Despite this, patients with osteosarcomas of the face generally have a better prognosis than those diagnosed with an extremity osteosarcoma.^{1, 4, 9}

Because of the scarcity of guidelines, treatment of head and neck osteosarcomas is based heavily on data from case reports and treatment modalities utilized against osteosarcomas of other body regions. Management strategies include multidrug chemotherapy, wide-margin radical resection, and radiation therapy.⁹ Treatment often varies based on patient and tumor characteristics, with larger, more aggressive, and high-grade lesions typically receiving multimodal therapy, including multidrug chemotherapy, to decrease the tumor size prior to radical resection and radiation therapy.