Giant Cell Tumor of the Bone

Giant cell tumor of bone or GCT is a rare, aggressive non-cancerous tumor that generally occurs in adults between the ages 20 and 40. They frequently occur around the knee joint in the lower end of the thighbone or the upper end of the shinbone. They can also occur in the wrist, hip, shoulder and lower back. Giant cell tumors are rare overall, affecting only 1.7 per 1 million people. Still, GCTs account for 15 to 21 percent of all benign tumors that start in your bones.

Types & Stages

There are two types of giant cell tumors:

• Osteoclastoma giant cell tumor. Also called giant cell tumor of bone. These occur after bone growth is complete, so they usually don’t appear in children or teens. They seldom occur in older adults.
   
• Tenosynovial giant cell tumor. Also called giant cell tumor of the tendon sheath. These giant cell tumors grow in the soft tissue around your bones. They usually occur in people ages 25 to 50.

Signs & Symptoms

Symptoms of giant cell tumor of bone may include:

• a visible bump
• bone break (fracture)
• fluid buildup in the joint nearest the affected bone
• limited movement in the nearest joint
• swelling
• pain at the nearest joint

Diagnosis

Tests and procedures to diagnose GCTs may include:

• Imaging tests. These may include:
   
  • X-ray. This test uses a small amount of radiation to make images of tissues, bones and organs on film.
     
  • Radionuclide bone scan. This is a nuclear imaging test. It can show any degenerative or arthritic changes in the joints, find bone diseases and tumors, and find the cause of bone pain or inflammation. This test helps to rule out any infection or fractures.
     
  • Computerized tomography scan (CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. 
     
  • Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
     
• Biopsy. A procedure to remove some cells for testing. The sample might be removed with a needle put through the skin. Or the sample might be taken during surgery to remove the cancer. The type of biopsy depends on the cancer's location.

Treatment

The goal for treatment of a giant cell tumor is to remove the tumor and prevent bone damage. If untreated, GCTs will continue to grow and destroy bone. Treatment may include:

• Surgery. Giant cell tumors usually require surgery. Surgical procedures for these tumors include:
  • Curettage. Your doctor will use special tools to scrape the tumor away from the bone. It's the most commonly used way to treat giant cell tumors.
     
  • Bone graft. After your doctor does the curettage, they'll fill in the cavity with another piece of bone to stabilize the joint. The new bone may come from another part of your body (such as the hip) or a donor.
     
  • Bone cement mixture. Instead of a bone, doctors may use a special bone cement to fill the hole left by the tumor. They'll also place chemicals (such as liquid nitrogen, hydrogen peroxide or phenol) into the bone cavity to reduce the risk of the tumor coming back.
     
  • Placement of artificial joints or limbs. Doctors may need to remove a portion of your bone or a joint. Depending on the extent of your bone or soft tissue damage, you may need an artificial limb (prosthesis) to replace bone and an artificial joint to regain normal movement.
     
  • Removal of tissue lining. If the giant cell tumor was in your soft tissue, doctors may need to remove the tissue lining of the joint.
     
• Nonsurgical treatments. Your doctor may recommend the following options, either instead of or in addition to surgery:
   
  • Radiation therapy. If the tumor is in a place where surgery is difficult or impossible, radiation therapy may be able to shrink giant cell tumors. 
     
  • Tumor embolism. For this technique, doctors block off arteries that supply blood to the tumor. Doing so cuts off nutrients and oxygen and the cells of the tumor begin to die. Your doctor may do this before surgery, or they may use embolism alone to treat a giant cell tumor.
     
• Medicine.  Your doctor may treat some giant cell tumors with medicine when surgery isn't an option. 

Causes & Risk Factors

The exact cause of giant cell tumors is not known. But some risk factors include:

• Age. They tend to occur in individuals between 20 and 40 years old.
• Gender. They’re slightly more common in women than in men.
• Other conditions. In rare cases, GCTs may occur in people with hyperparathyroidism or Paget's disease of the bone. 

Screening

There is no routine screening for giant cell tumors.