Osteoblastoma-like osteosarcoma

We report an osteoblastoma-like osteosarcoma in the right proximal fibula i n a 22-year-old woman. Radiographs showed an ir regular osteolytic lesion f rom the metaphysis to the epiphysis in the proximal fibula with partial des truction of cortical bone. Tissue from a biopsy indicated a typical osteobl astoma. Curettage and bone graft was performed. One year after the surgery, local recurrence occurred, and a wide excision was performed. Histological examination of the enbloc surgical specimen revealed the tumor had permeat ed through the host bony trabeculae, although the nuclear atypia was not ma rked. Immunohistochemical expression of MIB-1 was detected in 9.0% of cells .