대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Osteosarcoma of the Rib

Radiologic Findings

On chest radiograph, about 4 x 5 cm sized mass is noted in right middle lung zone. Because the mass was associated with definte bony destrcution, it was regarded to be malignant primary bony tumor or metastatic rib tumor. CT scans show an extrapleural soft tissue mass, originating from the axillary portion of the right 6th rib. Osteolytic bone destruction in the rib with new bone formation within the soft tissue mass is also seen.
The tumor was completely resected en bloc. About 4 x 4 x 5 cm sized, highly vascular mass containing area of necrosis with extension to soft tissue, was noted. Pathological disgnosis was osteosarcoma, mainly osteoblastic type, originating from the right 6th rib.

Brief Review

The most commonly encountered tumors of the ribs are metastatic lesions. Primary tumors of the ribs are less common and about two-thirds of the primary tumors are malignant. The primary tumors of the ribs occur in descending order of frequency as follows: Chondrosarcoma 30%, Lymphoma, Myeloma (multiple or solitary) 17%, Fibrous dysplasia 12%, Osteosarcoma 10%, Osteochondroma 8%, Ewing's sarcoma 6%, Eosinophilic granuloma 3%, and numerous rare tumors (Hemangioma, Mesenchymal chondrosarcoma, Primitive neuroectodermal tumor in infancy, Parosteal chondroma, Chondroblastoma, Chondromyxoid fibroma, Giant cell tumor, Giant cell tumor of Paget's disease, Giant cell tumor of hyperparathyroidism, Nonossifying fibroma, Fibrous histiocytoma, Osteoid osteoma, Osteoblastoma, Aneurysmal bone cyst, fibrosarcoma, and angiosarcoma).
Metastatic carcinoma involves the thoracic skeleton via hematogeneous or lymphatic system or by direct extension. The most common primary tumors are breast, lung, prostate, thyroid, and kidney. Lymphoma may be centered in the rib, where they produce lytic destruction.
Chondrosarcoma is a tumor of adulthood, with the peak incidence of sixth decade. It commonly arises from the anterior costochondral or sternochondral junction of the upper four ribs. Secondary chondrosarcoma arises in the pre-existing enchondroma or osteochondroma. Radiologic features of malignant chondrosarcoma over a benign chondroma are ill-defined margins, cortical thickening, and breakthrough of the cortex. Amorphous, speckled calcification is a characteristic finding of chondroid matrix.
Ewing's sarcoma is primarily confined to the pediatric population, rare over 30 years old. The lesions are usually lytic, permeative appearance and produce lamellar periosteal reaction. Multiple myeloma expand the rib with complete erosion of cortex. Pathologic fractures are common. An enchondroma appears as a round or oval radiolucency, which may cause expansion of the bone and thinning of the cortex. Osteochondromas grow at right angles to the bone. The cortex of normal bone is continuous with the cortex of the osteochondroma. Fibrous dysplasia produce increased density or sclerosis, obscuring the normal definition of bony cortex. It can produce lytic lesions with thinning of the cortex and expansion of the rib.
Osteosarcoma(osteogenic sarcoma) constitute 40% of all primary malignant neoplasm of bone. Most patients are between the ages of 10 and 25 years and male to female ratio is 2 : 1. The proliferating tumor cells produce osteoid or immature bone. The most typical sites of involvement are metaphyses of the tubular bones in the appendicular skeleton (80%), particularly the femur (40%), the tibia (16%), and the humerus (15%). Osteosarcomas are relatively infrequent in the fibula, innominate bone, mandible, maxilla & spine and are rare in the skull, ribs, scapula, clavicle, sternum, radius, ulna, and small bones of hands and feet.

References

1. Mirra JM. Unique tumors of the ribs. In Mirra JM, Picci P, Gold RH. Bone tumors Clinical, radiologic, and pathologic correlations. Philadelphia: Lea & Febiger, 1989
2. Chiles C. The chest wall and pleura. Normal and abnormal. In Newell Jr. JD, Tarver RD. Thoracic radiology. New York: Raven press, 1993.
3. Park YK, Choi SE, Ryu KN. Well-differentiated osteosarcoma of the rib. J Korean Med Sci 1998;13:428-30
4. Abdulrahman RE, White CS, Templeton PA, Romney B, Moore EH, Aisner SC. Primary osteosarcoma of the ribs: CT findings. Skeletal Radiol 1995;24:127-9

Keywords

Chest wall, Rib, Malignant tumor,