High grade surface osteosarcoma: a clinicopathologic study of 46 cases

BACKGROUND: High grade surface osteosarcoma is a rare subtype of osteosarcoma arising on the surface of bone, accounting for only 8.9% of surface osteosarcomas at the study institution. METHODS: This study reviews 46 cases of high grade surface osteosarcoma, comprised of 13 cases from the Mayo Clinic files and 33 from the authors' files. Histologic features were reviewed in all cases, and radiographs were reviewed in 29 cases. RESULTS: There was a definite male predominance, and 70% of the patients were in the second and third decades of life. Forty-four of the 46 patients had lesions involving the long bones, the most common site being the midportion of the femur. Radiographically, the majority of lesions showed dense to moderate mineralization with a fluffy, immature appearance. Radiating spicules of bone perpendicular to the long axis of the bone, characteristic of periosteal osteosarcoma, were sparse. Histologic findings were identical to those of conventional osteosarcoma. Overall, survival at 5 years was 46.1%. Statistical analysis revealed that marginal excision was associated with an increased risk of local recurrence and that the patients with Broders Grade 3 tumors had a better prognosis than those with Grade 4 tumors. A good response to chemotherapy was associated with better clinical outcome. CONCLUSIONS: High grade surface osteosarcoma is a rare subtype of surface osteoscarcoma that has a prognosis similar to that of conventional osteosarcoma, in contrast to the more common type of osteosarcoma arising on the surface of bone. Wide excision and effective systemic chemotherapy are associated with better clinical results.