Report of four cases with high-grade surface osteosarcoma.

High-grade surface osteosarcoma is the rarest of the three types of surface osteosarcoma. Four cases with high-grade surface osteosarcoma arising from the distal femur and tibia are reported in this study. One patient was previously diagnosed with Turner's syndrome. Radiologically, three cases presented characteristic appearances suggesting high-grade bone-forming sarcoma arising from the bone surface; however, one case was similar to other juxtacortical lesions such as periosteal and parosteal osteosarcoma, which typically have a better prognosis than high-grade surface osteosarcoma. Therefore, all cases underwent biopsy to determine a definitive diagnosis. Our strategy of treatment for high-grade surface osteosarcoma was a combination of wide resection and pre-/post-operative chemotherapy, equivalent to the treatment for conventional intramedullary osteosarcoma. At the last follow-up, two cases were still undergoing chemotherapy, one case was continuously disease free during the follow-up period of 81 months, and one patient was living with no evidence of disease 60 months after surgery. The aim of this study is to report the clinical information, oncological outcome and appropriate treatment for high-grade surface osteosarcoma.