Bone tumors, primary malignant
A rare type of bone cancer, primary malignant bone tumors (sarcomas of the bone) constitute less than 1% of all malignant tumors. Most malignant bone tumors are secondary, caused by seeding from a primary site. Primary malignant bone tumors are more common in males, especially in children and adolescents, although some types do occur in patients between ages 35 and 60.
The tumors may originate in osseous or nonosseous tissue. Osseous bone tumors arise from the bony structure itself and include osteogenic sarcoma (the most common), parosteal osteogenic sarcoma, chondrosarcoma (chondroblatic), and malignant giant cell tumor. Together they make up 60% of all malignant bone tumors. Nonosseous tumors arise from hematopoietic, vascular, and neural tissues and include Ewing’s sarcoma, fibrosarcoma (fibroblastic), and chordoma. Osteogenic and Ewing’s sarcomas are the most common bone tumors in childhood. (See Types of primary malignant bone tumors, pages 108 to 109.)
Causes
Although some cases of osteosarcoma are associated with genetic abnormalities (retinoblastoma, Rothmund Thomson syndrome) or exposure to carcinogens (such as ingested radium in watch dial painters), most cases have no immediately apparent cause. Ewing’s sarcoma cells demonstrate a characteristic translocation of genetic material from chromosome 22 to chromosome 11. Additional theories point to heredity, trauma, and excessive radiation therapy.
Signs and symptoms
Age AlertLimb pain and refusal to walk with limited range of motion are common findings in children with bone tumors.
Bone pain is the most common indication of a primary malignant bone tumor. It’s usually more intense at night and isn’t usually associated with mobility. The pain is dull and usually localized, although it may be referred from the hip or spine, which result in weakness or a limp. Another common sign is the presence of a mass or tumor.
The tumor site may be tender and swell; the tumor itself is often palpable. Pathologic fractures are common. In late stages, the patient may be cachectic, with fever and impaired mobility.
Diagnosis
A biopsy (by incision or by aspiration) is essential for confirming a primary malignant bone tumor. Bone X-rays and radioisotope bone and computed tomography (CT) scans show tumor size. Serum alkaline phosphatase levels are usually elevated in patients with sarcoma.
Clinical TipBone X-rays, CT scans, and magnetic resonance imaging are all useful in assessing tumor size. Bone scans and CT scans of the lungs are important in checking for metastatic disease.
Treatment
Excision of the tumor along with a 3″ (7.6 cm) margin is the treatment of choice. It may be combined with preoperative chemotherapy.
In some patients, radical surgery (such as hemipelvectomy or interscapulothoracic amputation) is necessary. However, surgical resection of the tumor (often with preoperative and postoperative chemotherapy) has saved limbs from amputation.
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