An unusual case of primary osteosarcoma of the rib in an adult

Primary osteosarcomas are one of the most common malignant bone tumors principally affecting the long bones in children and adolescents. An unusual case of a primary osteoblastic osteosarcoma of the rib in a 42-year-old male is presented here. The patient underwent a wide excision of the tumor and chest wall reconstruction. Although clinically unsuspected in this unusual site, the classic microscopic feature of a ramifying osteoid matrix amidst the tumor cells was diagnostic of an osteosarcoma.