Pediatric surface osteosarcoma: clinical, pathologic, and radiologic features

Osteosarcoma (OS) arising from the surface of bone is far less common than its intramedullary counterpart. Although surface OSs share some radiographic and clinical features, they can be divided into three distinct histologic subtypes.

We reviewed the clinical, radiographic, and pathologic features of 14 cases of pediatric surface OS treated at St. Jude Children's Research Hospital between 1970 and 2003.

Seven patients had parosteal, five had periosteal, and two had high-grade surface OS. The median age at diagnosis was 16.2 years (range, 13.6-18.5 years). Nine patients were male; 11 were Caucasian. None had metastatic disease at diagnosis. Primary tumor sites included distal femur (n = 6), mid to proximal femur (n = 4), and mid to proximal tibia (n = 4). All 14 patients were treated with surgery, and 7 (1 with parosteal, 4 with periosteal, 2 with high-grade tumors) received chemotherapy. One patient experienced pulmonary metastasis of periosteal OS 16 months and 43 months after diagnosis; long-term disease-free survival followed resection of the metastatic tumors. Twelve patients remained alive and disease-free a median of 10 years (range, 1.5-25.4 years) after diagnosis. One patient died of high-grade surface OS 1.8 years after diagnosis, and one patient with periosteal OS died of gastric cancer 18.2 years after diagnosis of OS.

The histologic grade predicts the clinical behavior of pediatric surface OS. Complete resection is the treatment of choice regardless of tumor subtype. Whereas chemotherapy is not indicated for parosteal OS, its role in periosteal OS remains controversial.