Primary parosteal osteosarcoma of the rib.

Osteosarcoma is a common primary malignant tumour of bones that produces an osteoid matrix. Parosteal osteosarcoma is an uncommon neoplasm and principally affects the long bones, especially in the distal femur, proximal tibia and proximal humerus. Rarely, the tumour may arise in a flat bone, and rib involvement is very infrequent. An unusual case of primary parosteal osteosarcoma of the rib in an asymptomatic 28-year old female is presented here. A chest X-ray film suggested an intrapulmonary homogeneous mass, while a computed tomography scan revealed a broad-based calcified mass attached to the inner cortex of the right fourth anterior rib. The patient underwent a wide excision of the tumour together with adjacent intercostal muscles and chest wall reconstruction. Postoperative histopathological outcome was consistent with primary parosteal osteosarcoma.