Case 3: 58-year-old woman. (A) An incisional biopsy of the distal femur was performed using a lateral approach, and bone metastasis of uterine leiomyosarcoma was diagnosed. The skin around the biopsy, a part of the vastus lateralis muscle, and the vastus intermedius muscle were resected along with the bone tumor. Reconstruction was then performed with a megaprosthesis. Based on the pathological examination of the surgical specimen, conventional osteosarcoma was diagnosed, and postoperative chemotherapy (methotrexate + doxorubicin + cisplatin regimen) was administered. (B) Three years after surgery, a mass was found on the distal lateral aspect of the left thigh; this was diagnosed as local recurrence by needle biopsy. (C–E) Wide resection of the tumor including the vastus lateralis muscle and the iliotibial tract was performed, and the megaprosthesis was covered with a sartorius muscle flap. The patient had no evidence of disease 5 years 6 months after the diagnosis of osteosarcoma.