Osteosarcoma

Epidemiology

Osteosarcomas usually involve the long bones and are most commonly diagnosed during childhood. However, head and neck osteosarcomas are mostly found in adults and these tumors account for 7 to 16% of all osteosarcomas. The most common site in the head and neck is the mandible. Skull base tumors are rare. There is a known relationship between the development of osteosarcoma with Paget’s disease, fibrous dysplasia, bilateral retinoblastoma, and irradiation.

Clinical Findings

Patients with osteosarcoma usually present with a mass with or without pain. Most of these tumors are large at presentation. Clinically, the mass is rock hard. Lesions located in the skull base or deep face may have less obvious mass effect or facial deformity.

Pathology

The cell of origin is the osteoblast. Osteosarcomas are very pleomorphic. If they are well differentiated, osteoid formation is evident. Osteoids may show variable calcification or ossification. When these lesions breach the bone cortex, they lift the periosteum. New bone with the typical sunray appearance may form beneath the periosteum. The tumor frequently metastasizes and the most common site for secondaries is the lung.