Description

Giant cell tumors of bone are benign, multinucleated masses of cells commonly found in the epiphysis and sometimes in the metaphyses of long bones, they could appear in tendon sheaths. These tumors get their name due to the large appearance of the cell under the microscope.

Giant cell tumors are discrete and locally aggressive abnormal growth or tumor that can metastasize to other areas of the body. The metastatic forms of giant cell tumors are known as malignant sarcomas, though this form of giant cell tumor is very rare. Giant cell tumors of the bone are one of the most challenging benign bone tumors due to resulting substantial bone damage, local reoccurrence, lung metastasis, metastasis to lymph nodes, and malignant transformation.

Prevalence

Giant cell tumors are rare and occur in approximately one in one million people annually. In the United States, 5% of all primary bone tumors and 21% of all benign bone tumors are giant cell tumors. Significantly higher incidence rates are observed in the Chinese population compared to the Western Caucasian population where giant cell tumors constitute up to 20% of the affected population.

The most common cases of giant cell tumors are in skeletally mature patients between the ages of 20 and 55 years, with the highest incidence in the third decade of life. Females have a 3/2. greater risk of developing giant cell tumors than males

These tumors most often affect the epiphyseal ends of long bones such as the femur and tibia. The most common sites of appearance are around the knee in 60% of cases, and in the sacrum which is rare but still the third most common site.

Although the tumor occurs in the lungs. When metastasis travel to the lung, they appear as clusters within the lung. It spreads at a slow rate and usually does not appear until 3-5 years after a patient is diagnosed with a primary bone tumor.

Clinical form

Many symptoms depend on the location of the tumor. Here are the most common signs and symptoms that a patient may have:

• Pain in the area of the tumor that gradually increases

• Pain that increases with activity and decreases with rest

• Decreased the joint’s range of motion

• Hard mass may be palpated

• Muscle atrophy

• High skin temperature above the lesion

• Swollen area

If there is significant damage to the bone at the site of the tumor and the layer of the bony cortex is damaged, a pathological fracture may occur. If the tumor is in a weight-bearing bone, the patient will complain of severe pain when carrying the weight.

When the sacrum is injured, lower back pain and disability will result in that may spread to the lower legs. with local swelling. The patient may also complain of abdominal pain, neurological problems such as bowel and bladder dysfunction, sexual dysfunction, numbness, and weakness in the lower extremities.

Medications

Bisphosphonates

This drug is not used as a treatment for the giant cell tumor itself but is used to inhibit the destruction of bone tissue where the giant cell tumor is located. It works by inhibiting

bone resorption. Research indicates that bisphosphonates may be useful in managing disease advancement in giant cell tumors of bone and these agents have been found to directly inhibit the giant cell tumor.

Diagnostic tests and laboratory tests

Giant cell tumors are usually diagnosed by X-ray and verified by histological examination. Below is a list of diagnostic tests that can be used to help identify and differentiate the type of tumor

• Tumor biopsy: A sample of the tumor is taken and examined under a microscope and allowing determining how aggressive the tumor is. The tumor’s cellular composition is then examined to exclude other malignancies that may resemble a giant cell tumor.

• X-ray: Giant cell tumors appear as transparent lesions within the bone that are usually near the joint line. The affected part of the bone is surrounded by a slim border of white bone. Sometimes the bone in the area of the tumor bulges outward. Chest X-rays should be done to detect a lung malignancy.

• Magnetic resonance imaging: to produce detailed images of the internal tissues inside the body.

• CT scan: CT scans are more detailed than X-rays and can show images of bones, muscles, fats, and organs. CT scans of the lungs of patients with giant cell tumors are often done to check for signs of lung malignancy.

• Bone scan: This is used to help diagnose whether a tumor is present and whether it has spread to other areas of the body. A bone scan will show a ‘hot spot’ at the site of the tumor in the bone tissue.

• Blood tests: blood count and blood chemistry tests

Etiology:

Giant cell tumors occur spontaneously with no known etiology.

Systemic Involvement

• Joint pain with limited range of motion

• Pathological fracture

• Muscle atrophy

• Overheating of the overlying skin

• Swelling at the site of the tumor

• Intestinal and bladder weakness

• Impotence

• Numbness and weakness in the lower extremities

• Possibility of lung injury in the event of metastases

Management:

Surgical excision is the most successful treatment option. By scraping the tumor, the space in the bone is filled with a bone graft either from the patient’s own body or a heterograft prepared by another person. This treatment method has a recurrence rate of up to 45%. Therefore, bone cement is often used, this method has a lower rate of tumor recurrence.

If the tumor is difficult to reach or can only be partially removed, radiation therapy may be used as a treatment option, although it is never the primary treatment of choice. Radiotherapy has been discussed and used only for patients who are not candidates for surgery due to the high rates of recurrence.

Treatment of giant cell tumors may require one or more of the following surgical interventions:

Curettage: The most common surgical treatment in which the tumor is excavated from the bone with a scoop.

Cryotherapy: It can be used. After the tumor is removed, liquid nitrogen is placed in the space left by the tumor to freeze the area. The cycle of freezing and thawing is repeated one to two times to help destroy any remaining cancer cells and prevent them from growing.

Bone Grafting or Cement Packing: The hole left by a tumor is often filled with bone from other parts of the body (autograft), donor bone tissue (allograft), or bone cement.

Block resection: It is a more aggressive procedure to remove the tumor in which the surgical removal of the bone as a large lump that contains the tumor is performed. Fixing internally with pins is often necessary to provide stability. If large amounts of bone are removed, a bone from a donor or mineral substitutes will be used for bone resection.

After the treatment, the patient must make several follow-up visits with his doctor to perform physical examinations and x-rays of the tumor site and the lungs to ensure that it has not relapsed or moved, for a period of at least 5 years.

Physical Therapy:

Physiotherapy will also be incorporated into the treatment plan to remove any disabilities or functional limitations such as tumor complications. The goals of physical therapy are to improve patients’ quality of life and to allow them to live independent lifestyles. The main areas of physical therapy are reducing pain, improving movement, and restoring previous levels of function. This will be achieved first by educating the patient about their condition, making them aware of what they should and should not do about their condition, and emphasizing the importance of staying active. Physiotherapy will also focus on improving the cardiovascular status and endurance to prevent fatigue and exhaustion through daily activities. It is important to focus on maintaining flexibility through stretching and range of motion to allow good movement and reduce joint stiffness and pain. A combination of light-strengthening exercises and balance activities should also be incorporated to allow the patient to complete daily tasks safely and effectively.

Differential Diagnosis:

Symptoms of giant cell tumors are usually minor in nature and often resemble that of musculoskeletal origin. Sacral tumors usually go undiagnosed due to their characteristics similar to low back pain.

Other bone tumors that should be excluded from the histological analysis are:

• Brown tumors of hyperparathyroidism

• Aneurysmal bone cysts

• Chondroblastoma

• Osteoblastoma

• Osteosarcoma