Malignant tumors of bone may originate in the bone or metastasize to the bone. There are definite patterns in tumor type based on the age of the patient.
Ewing's sarcoma is a tumor of uncertain origin. It is most common in children and young adults. It is more common in whites than blacks. The tumor may occur in any bone but has some predilection for long tubular bones and the pelvis. The presenting complaints include pain, swelling, tenderness, and erythema, which makes it resemble osteomyelitis. Early there may be no radiographic abnormalities, but later a typical lytic lesion with an "onion-skin" appearance of the periosteum is seen. The prognosis is improving with the use of surgery, chemotherapy, and in some cases radiotherapy. Long-term cures are now seen in about 50% of five-year survivors.27
A cartilage-producing bone tumor, primary chondrosarcoma occurs most commonly during middle to late life. It occurs most commonly in the central skeleton. The tumors are slow-growing and late in metasta-sizing, resulting in a relatively favorable prognosis. They are graded on the basis of anaplasia, and most of the tumors fall into the low anaplas-tic categories.27 Because they are slow-growing, patients may present with a bony mass that has been present for years. Radiographs demonstrate radiolucent lesions with increased uptake on bone scintigraphy.29 Successful treatment requires total removal of the tumor. The specimen's pathological analysis has prognostic value, with the lower grades of anaplasia being associated with a higher five-year survival.
Osteosarcoma is an aggressive tumor of mesenchymal cell origin characterized by formation of bone by the tumor. Except for myeloma, it is the most common primary bone cancer. These tumors can generally be split into primary and secondary types. Primary osteosarcomas occur most commonly in children and young adults and are most common in males. There appears to be a genetic predisposition. The secondary osteosarcomas generally develop in adults in areas of abnormal bone (e.g., Paget's disease) or in response to some sort of carcinogen exposure (most commonly irradiation). The most common presenting complaints of patients with osteosarcoma are local pain, tenderness, and swelling. It most often occurs in the medullary cavity of the metaphyseal end of the long bones of the extremities. Radiographs, computed tomography (CT) scans, or MRI scans often provide a characteristic picture of subperiosteal or soft tissue penetration of the tumor with extraosseous bone density. To confirm the diagnosis, however, biopsy is required. Great advances have been made in treatment recently, with a combination of surgery, radiotherapy, and chemotherapy (depending on the specific type of lesion) providing the best chances for survival.27
Chordoma is a malignant bone tumor seen most commonly in the sacrum and spine. It is thought to arise from remnants of the noto-chord. These tumors are usually seen in middle-aged and elderly adults. Radiographs, CT scans, or MRI scans usually show the mixed lytic and sclerotic lesions of the chordoma.30
Tumors that commonly metastasize to bone include thyroid, breast, prostate, bronchus, kidney, bladder, uterus, ovary, testicle, and adrenal tumors. Lymphomas most commonly spread to bone from primary involvement of lymph nodes but also are seen rarely primarily in the skeleton. Bone scans are thought to be the best screening test for patients suspected of having skeletal metastasis.31 Patients with metastatic bone disease most often present with pathological fracture or pain. The radiographical appearance of these lesions tends to be sclerotic in prostate and breast metastasis and lytic in lung, bowel, kidney, and thyroid. Biopsy of the bony lesion is helpful for determining whether the lesion is metastatic.
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