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Giant cell tumor of bone (GCT) is a rare, aggressive non-cancerous (benign) tumor. It generally occurs in adults between the ages of 20 and 40 years. Giant cell tumor of bone is very rarely seen in children or in adults older than 65 years of age. Giant cell tumors occur in approximately one person per million per year.
Giant cell tumors are named for the way they look under the microscope. Many "giant cells" are seen. They are formed by fusion of several individual cells into a single, larger complex. Many bone tumors and other conditions (including normal bone) contain giant cells. Giant cell tumor of bone is given its characteristic appearance by the constant finding of a large number of these cells existing in a typical background.
Most bone tumors occur in the flared portion near the ends of long bone (metaphysis), but giant cell tumor of bone occurs almost exclusively in the end portion of long bones next to the joints (epiphysis). Giant cell tumors of bone most frequently occur around the knee joint in the lower end of the thighbone (femur) or the upper end of the shinbone (tibia). Other common locations include the wrist (lower end of the lower arm bone), the hip (upper end of the thighbone), the shoulder (upper end of the upper arm bone), and lower back (connection of the spine and pelvis).
In rare cases, this tumor may spread to the lungs.
Giant cell tumors of bone occur spontaneously. They are not known to be associated with trauma, environmental factors, or diet. They are not inherited. In rare cases, they may be associated with hyperparathyroidism.
The first symptom most patients notice is pain in the area of the tumor. There may be pain with movement of a nearby joint. Pain generally increases with activity and decreases with rest. Pain is usually mild at first, but it progressively increases.
Occasionally, the bone weakened by the tumor may break and cause sudden onset of severe pain. Sometimes patients will notice a mass or swollen area that may not be painful.
Often a doctor may use magnetic resonance imaging (MRI) and computed tomography (CT) scans. These can help better evaluate the area of involvement.
A bone scan generally shows a "hot spot" in the bone where the tumor is. An x-ray or CT scan of the chest will often be done to look for possible spread to the lungs.
If not treated, these tumors will continue to grow and destroy bone. Surgery has proven to be the most effective treatment for giant cell tumors.
Radiation therapy is a nonsurgical treatment option that has proven effective. However, this can result in the formation of cancer in as many as 15% of patients who receive it. Therefore, radiation therapy is used only in the most difficult cases where surgery cannot be performed safely or effectively.
Scooping out the tumor (curettage) is generally performed. This technique causes a hole in the bone that can be filled with a bone graft. The bone may be taken from other parts of the patient's own body (autograft) or from a cadaver (allograft).
If treatment is limited to curettage and bone grafting alone, the tumor may come back (recur) up to 45% of the time. The use of bone cement rather than bone graft results in a lower rate of recurrence.
Enhancing the curettage with a high-speed burr or with the use of agents such as liquid nitrogen, hydrogen peroxide, or phenol, followed by placement of bone cement decreases the recurrence rate to 10% to 29%.
More complex tumor removal and reconstruction is sometimes necessary in situations where the tumor has caused excessive damage or recurred.
In the rare cases where the tumor has spread to the lungs, surgical removal of the tumor in the lungs results in cure 75% of the time.
The American Academy of Orthopaedic Surgeons
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