Review Question - QID 214766

A 15-year-old male presents to your office for evaluation of a right proximal tibial mass. Two tissue biopsies were obtained at an outside institution 5 days prior. The first biopsy was performed percutaneously through the posterior aspect of the lower leg. After concern that not enough tissue was obtained, a second biopsy was performed through an open lateral approach and sent for pathology. Both samples came back as “high grade osteosarcoma”. On exam, the patient has mild tenderness to palpation along the biopsy sites and significant ecchymosis and hematoma extending down the lower leg and in to the foot. A chest CT was obtained and negative for metastatic disease. Which of the following is the most appropriate treatment for this patient?