What Is Tenosynovial Giant Cell Tumor?

Medically Reviewed by Dan Brennan, MD on June 03, 2023
4 min read

Tenosynovial giant cell tumor is a group of rare tumors. They’re typically benign -- not cancerous -- but they may cause pain, swelling, and inflammation.

‌Tenosynovial giant cell tumor is known as TGCT or TSGCT.

‌‌The worldwide rate of localized tenosynovial giant cell tumors is 10 cases per million. For diffuse or widespread tenosynovial giant cell tumors, this is 4 per million.

‌Based on a 1980 study, about 1.8 per 1 million people in the US are estimated to have tenosynovial giant cell tumors.

Tenosynovial giant cell tumors tend to affect those between the ages of 25 and 50 years. But young children and older people can get it as well. 

‌These tumors affect the following areas of your joints:

  • Synovium. This is a thin layer of membrane or tissue that lines the inside of your joints.
  • Bursae. These are small sacs of fluid that cushion the moving parts around your joints. These parts include bones, muscles, and tendons.
  • Tendon sheath. This is a layer of tissue that surrounds your tendons. Tendons are the connective tissue that connects your muscles to your bones.

‌These tumors typically aren’t cancerous, but there have been some very rare cases of malignancy, with amputation needed in some.

There are two subtypes of tenosynovial giant cell tumors - localized or diffuse.

Giant cell tumors of the tendon sheath (GCTTS). These small tumors usually are limited to a specific area of the joint, which means they’re localized. Usually, this affects your smaller joints, like those in your hands and feet.‌

Pigmented villonodular synovitis (PVNS). These are diffuse or widespread tumors that usually affect the entire joint. In most cases, just one joint is involved. Usually, this is the knee, followed by the hip. Other joints that may be affected are the ankle, shoulder, or elbow. 

‌Even after treatment, about 8% to 20% of people with localized tenosynovial giant cell tumors may get it again. The widespread type recurs more often, in about 33% to 50% of people.

‌These tumors are caused by the translocation of certain chromosomes. Chromosomes carry your genetic information. Each of your cells normally has 46 chromosomes. In a chromosomal translocation, some chromosomes break off and are rearranged. The reason for this is unknown.‌

‌Tenosynovial giant cell tumors are caused by a translocation of certain parts of chromosomes 1 and 2. This causes the cells to overproduce a protein called colony-stimulating factor-1 or CSF-1.‌

‌These CSF-1-producing cells attract other cells that have a CSF-1 receptor. Cells with the CSF-1 receptor are called macrophages, a type of white blood cell. When these cells join together, they form a tenosynovial giant cell tumor.

‌The symptoms of tenosynovial giant cell tumor depend on which subtype you have. Some possible symptoms include the following:

  • ‌Swelling that may be painless at first 
  • ‌Warmth or tenderness around your joint
  • ‌Locking, popping, or catching when you move your affected joint
  • ‌Unstable joint

Diffuse-type tenosynovial giant cell tumor (pigmented villonodular synovitis) can cause degeneration of your joints. It can also damage the bone and cartilage that surrounds your affected joint. If left untreated, it can cause chronic pain and deterioration of your joints.‌

Giant cell tumor of the tendon sheath is less likely to cause destructive damage to your joint, bone, and cartilage.

‌Your doctor will discuss your symptoms, take a detailed history, and order some tests. X-rays and magnetic resonance imaging (MRI) can help to diagnose these tumors. 

Your doctor may also take a sample of your synovial fluid. This is the fluid that’s found in your joints. If you have a tenosynovial giant cell tumor, this fluid may have blood in it.‌

‌In some cases, a biopsy may be needed to confirm the diagnosis. A biopsy lets your doctor see what kind of cells the tumor has. This will help your doctor differentiate between pigmented villonodular synovitis and giant cell tumor of the tendon sheath. 

‌Treatment of tenosynovial giant cell tumors depends on its potential to progress as well as its location.

Surgery. Surgery is the main treatment for tenosynovial giant cell tumors. Your doctor may remove some or all of the tumors, as well as the inflamed joint tissue. You may need another surgery if the tumor returns.

‌The tumors can be removed by open surgery or arthroscopic surgery, which is a less invasive procedure. In arthroscopy, your surgeon makes a few small cuts around your joint. A small camera is inserted to help guide the surgery. 

In some cases, a combined open and arthroscopic surgery may be needed. 

In advanced cases, you may need total joint replacement surgery. Your surgeon will remove parts of your damaged joint, and replace it with plastic, metal, or ceramic parts. 

Radiation therapy. This may be used alone or in combination with surgery.‌

‌Radiation therapy is typically done via external beam radiation. But in recent years, a method called intra-articular radiation, or isotopic synoviorthesis, has been used. This brings the radiation directly into your affected joints. ‌

Potential therapies. A few medications are being studied for the treatment of these tumors. They block the CSF-1 receptors and are undergoing clinical trials. 

‌The Food and Drug Administration (FDA) has approved pexidartinib as a treatment for tenosynovial giant cell tumor. A clinical trial showed that pexidartinib significantly improved the range of motion in the affected joint when compared with the placebo.