[Parosteal osteosarcoma of the femur and salvage surgery with intercalary prosthesis. Experience in a third level unit and surgical technique].

Introduction: parosteal osteosarcoma is an extramedullary malignant bone tumor in which cells produce osteoid, represents less than 5% of all osteosarcomas, it occurs predominantly in women between the second and fourth decade of life. It is often located in the distal region of the femur and proximal tibia. Clinically it presents with increased volume and thigh or knee pain.