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Giant Cell Tumor

A giant cell tumor is a rare, non-cancerous growth that occurs at the end of a bone near a joint. Giant cell tumors can form in the legs, wrists, and hips of people who are in their 20s and 30s. Doctors usually treat giant cell tumors with surgery.

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What Are Giant Cell Tumors? 

Doctors define giant cell tumors as benign (non-cancerous) growths that occur on the end of a long bone next to a joint. They sometimes form in nearby soft tissue.

Doctors call these fast-growing clumps of cells "giant cell tumors" because of the way they look under a microscope. The tumors consist of unusually large cells because several individual cells merge into a single “giant” cell.

Giant cell tumors are aggressive and fast-growing. Even though they aren’t life-threatening, they can cause pain and damage by destroying nearby healthy bones. 

Typical places for a giant cell tumor of bone to grow include:

  • Hip, at the upper end of the thighbone.
  • Knee joint, either at the lower end of the thighbone or the upper end of the shinbone.
  • Lower back, where the spine and pelvis connect.
  • Shoulder, at the upper end of the upper arm bone.
  • Wrist, at the lower end of the lower arm bone.

How common are giant cell tumors?

Giant cell tumors are very rare. They only occur in one out of a million people in the U.S. every year. They're slightly more common in women than men. 

Giant cell tumors typically occur in people aged 20 to 40.

What are the types of giant cell tumors?

There are two types of giant cell tumors:

  • Osteoclastoma giant cell tumor — or giant cell tumor of bone. They happen 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 — or 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.

What causes giant cell tumors? 

The cause of giant cell tumors is unknown.

The tumors may begin to form when there’s a change in your chromosomes. People with overactivity of the parathyroid gland (hyperparathyroidism) may be more likely to get giant cell tumors. But doctors haven’t found an exact reason why some people spontaneously get giant cell tumors. 

What are giant cell tumor risk factors and complications?

Because their cause is unknown, there's no way to prevent a giant cell tumor from forming.

Giant cell tumor risk factors

There are no known risk factors for giant cell tumors. They're not inherited, and environmental factors, diet, and trauma don't seem to play a part in their development. 

Complications of giant cell tumors

If left untreated, giant cell tumors can keep growing. Eventually, they'll cause pain and interfere with the movement of your joints. In rare cases, giant cell tumors can spread to the lungs.

Giant cell tumors sometimes recur after treatment.

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What Are the Signs and Symptoms of Giant Cell Tumors?

The symptoms of giant cell tumors include:

  • A broken bone that seems to happen for no reason. This occurs when the tumor weakens the bone. You may have a sudden, extremely painful break.
  • A joint that feels unstable, or locks or catches when you move it.
  • A joint that feels warm or tender.
  • A visible mass near the end of a bone.
  • Increasingly limited movement or stiffness in the joint near the tumor.
  • Pain near the tumor. At first, it may be mild but gets worse over time as the tumor grows.
  • Pain with movement of a joint. The pain increases when you’re active and decreases when you rest.
  • Swelling under the skin, which may be fluid buildup near the joint.

When should I see a doctor about my giant cell tumor symptoms?

If you have joint stiffness, swelling, or a painful bump under your skin, you should see your doctor. Since other health issues have symptoms similar to giant cell tumors, your doctor will have to rule out arthritis, stress fractures, and infections.  

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How Do You Diagnose Giant Cell Tumors?

Your doctor will ask you about your health history, your overall health, what medicine you take, your symptoms, and your family history. They'll also do a physical exam, focusing on the area where the tumor is.

Tests to diagnose giant cell tumors

To diagnose a giant cell tumor, your doctor may run the following tests:

  • Biopsy. A biopsy will confirm what kind of tumor you have. Doctors take a sample of tissue from the tumor using local anesthesia and a needle, or in a small operation, and then look at it under a microscope.
  • Bone scans. Doctors inject a small amount of radioactive dye into your body through a vein. Giant cell tumors will collect the radioactive material and appear as a “hot spot” in the bone where the tumor is.
  • Imaging tests. X-rays, CT scans, and MRIs help doctors evaluate the tumor to see whether it’s in a bone or soft tissue. They may order a chest x-ray to find out if the tumor has spread to the lungs.

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How Do You Treat Giant Cell Tumors? 

It’s important to treat giant cell tumors. Without treatment, they'll continue to grow and will eventually destroy healthy bones and impede movement. 

Your doctor will likely want to cut out the tumor to prevent the tumor from further damaging the bone and coming back. Depending on the tumor’s size and location, you may need surgery, medicine, radiation, or a combination of all three. 

Nonsurgical treatment for giant cell tumors

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. But radiation therapy carries the risk of cancer for some people, so your doctor will weigh the benefits against the risks.
  • 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. Doctors may do this before surgery, or they may use embolism alone to treat a giant cell tumor.

Medicine to treat giant cell tumors

Doctors may treat some giant cell tumors with medicine when surgery isn't an option. The U.S. Food and Drug Administration (FDA) recently approved pimicotinib, an injectable medicine for treating tenosynovial giant cell tumors.

This medicine works by targeting a special receptor on the giant cells, which decreases their activity. However, the tumor may recur after the treatment stops.

Surgery for giant cell tumors

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.

How effective is treatment?

Treatment for giant cell tumor is usually very successful. Because these tumors aren’t cancerous, they rarely spread.

Your recovery time will depend on how big the tumor was, where it was located, and what type of surgery your doctor performed. 

Giant cell tumors can recur, so you need to keep seeing your doctor for regular follow-up visits several years after treatment. Your doctor will take x-rays of the area where the tumor was to make sure it didn’t come back. They'll also take chest x-rays to make sure the tumor didn’t spread. 

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