What Is a Tenosynovial Giant Cell Tumor (TGCT)?
Tenosynovial giant cell tumors (TGCTs) are growths in the soft tissue in and around your joints. While they are tumors, they are benign. That means that they rarely spread to other parts of your body and they aren’t life-threatening.
It depends on where you have a TGCT, but they can make it hard for you to move your joint or the part of the body where it’s growing. They can damage your joint and the tissue around them. They also can be painful and affect your quality of life. TGCTs also can grow fast. If you have surgery to remove a TGCT, it may still come back, or recur.
The reason they’re called tenosynovial giant cell tumors is partly because of the way they look under a microscope. If you could zoom in and see it, they look like clusters of unusually giant cells.
The word “tenosynovial” comes from the places where these happen. TGCTs affect the synovium, the thin layer of tissue covering the surfaces of your joint spaces. They also can affect tendon sheaths, or the layer of membrane covering your tendons, which is the fibrous tissue connecting your muscles to your bones. You also can get TGCTs in your bursa, which are protective, fluid-filled sacs where your muscles, tendons, and bones meet.
Localized vs. diffuse TGCT
If your TGCT is localized, then it’s limited to a particular place. You can have a localized TGCT anywhere in your body where you have joints. They usually start as a small growth or nodule that’s connected to the affected part of your joint with a stalk. They also will look well-defined or encapsulated.
Most localized TGCTs will be in or around the joints of your fingers, hands, and wrists. It’s less common to get them in joints of your foot, ankle, knee, hip, or other joints. Doctors used to call a localized TGCT a giant cell tumor of the tendon sheath (GCTTS), tenosynovitis, or nodular synovitis.
Diffuse TGCTs tend to grow more aggressively and cause more problems. They’re called diffuse because they are spread out over a bigger area of your joint instead of being concentrated in a smaller, well-defined spot.
Diffuse forms happen mostly in your larger joints, including your:
Knee
Hip
Ankle
Elbow
Shoulder
More rarely, diffuse TGCTs can affect the joints connecting your jawbones to your skull or the joints between your spinal vertebrae.
Doctors used to call TGCTs pigmented villonodular synovitis (PVNS).
TGCT vs. ganglion cysts
A ganglion cyst is another type of growth or lump you can get around your joints. But ganglion cysts are filled with fluid and just under your skin unlike TGCTs, which grow in the tissue in and around your joints. If you have any type of lump or growth and you don’t know what it is, it’s a good idea to see your doctor.
Who Gets Tenosynovial Giant Cell Tumors (TGCTs)?
Tenosynovial giant cell tumors (TGCT) aren’t common, but anyone can get them. They happen more often in women and adults who were assigned female at birth. They most often happen between ages 30 and 50.
Less than 50 in every 1 million people around the world will get a TGCT each year. This makes them very rare. But if you’ve had one TGCT, you are likely to have it come back.
TGCTs don’t have any known risk factors that make them more likely or help to explain why some people get them and others don’t.
Tenosynovial Giant Cell Tumor (TGCT) Causes
It’s not clear what causes TGCTs. But up to 16% of the cells in the tumor will have a specific chromosomal abnormality.
Your cells normally have 46 chromosomes, which contain your DNA. The type of abnormality in TGCT is a chromosomal translocation. That means that a piece of one of your chromosomes has broken off and gotten attached to another chromosome. The specific translocation in TGCT involves parts of chromosomes 1 and 2.
The cells with this chromosomal abnormality make too much of a protein called colony stimulating factor-1 (CSF-1). Because of that, they attract certain other cells including white blood cells called macrophages. Most of the cells in your TGCT will be these macrophages and other cells that are attracted to the CSF-1 made by those abnormal cells. The macrophages and other cells in your TGCT likely cause the inflammation and other symptoms of TGCT.
While doctors now know the underlying causes for TGCTs, it isn’t clear why this happens. The chromosomal abnormality that leads to increases in CSF-1 might just happen randomly and for no reason.
Tenosynovial Giant Cell Tumor (TGCT) Symptoms
Common symptoms of TGCTs will arise in your affected joint or body part and include:
A bump or lump
Pain, especially when you move it
Swelling or inflammation
Catching, locking, popping, or stiffness in your joint
Unusually warm skin around your joint
Weak or unstable joints
Your symptoms will depend on:
Where your TGCT is
Which type of joint tissue your TGCT is in
How big it is
How fast it grows
Early symptoms of TGCT
Swelling is often one of the first things you’ll notice if you have a TGCT. You’re more likely to have pain earlier on if your TGCT is diffuse and more widespread. But either type can cause pain. You may also notice stiffness or trouble moving your joint that gradually gets worse. Because TGCT is rare and early symptoms aren’t clear, it’s likely you won’t recognize it at first.
Tenosynovial Giant Cell Tumor (TGCT) Diagnosis
TGCTs often get diagnosed years after symptoms develop. On average, TGCTs are diagnosed 3-4 years after symptoms start.
Your doctor will diagnose TGCTs based on your symptoms. They will ask you lots of questions about your medical history and give you a physical exam. They will likely order imaging tests including:
X-rays to rule out other conditions and look at any damage in your affected joint
Magnetic resonance imaging (MRI) to see more detailed changes in your joint and growth including blood vessels and deposits that are more specific to TGCTs
It’s important to know if your TGCT is localized or diffuse. Your doctor can tell from MRI images showing changes in the way your cells are acting.
Other tests
Your doctor might take a sample of your joint fluid. When you have a TGCT, your joint fluid may have blood in it.
They may also want to take a biopsy to help confirm that you have a TGCT. A pathologist can look at your joint tissue under a microscope to see what type of cells are in it. Many times, doctors can diagnose a TGCT based on MRI images alone.
Tenosynovial Giant Cell Tumor (TGCT) Treatment
Surgery is the most common first treatment for a TGCT if you have symptoms. If your TGCT is localized, surgery may cure it. But it will come back 10%-15% of the time.
Diffuse TGCTs are harder to remove with surgery. At least half the time, diffuse TGCTs that are removed with surgery come back. If you have a TGCT removed and it comes back, you’re even more likely to have other recurrences.
The type of surgery you have depends on where the TGCT is and how big an area is affected. There’s no standard way to remove TGCTs. You may have a synovectomy to remove the lining of your joint. You could have this done in an open surgery or arthroscopically, in which your surgeon will use a small instrument with a tiny camera.
If your TGCT is more severe or surgery doesn’t work, you could have a joint replacement. Doctors used to treat TGCT with radiation, but this isn’t recommended anymore.
Medicines to treat TGCT
A medicine called pexidartinib has been approved for symptomatic TGCT. It works by targeting colony stimulating factor-1 (CSF-1), the factor that causes the growths to form. You may treat your TGCT with this targeted therapy if your disease is more severe or it's limiting your ability to function. It’s also an option if your TGCT isn’t getting better or comes back after surgery.
Not everyone gets better with the medicine, but clinical trials showed that more than half of people are helped by it. Of those, 39% had a partial response and 18% had a complete response, meaning that their TGCT went away or could no longer be detected.
Sometimes doctors use other medicines off-label. That means that they are approved for other conditions but not TGCTs. Other potentially promising therapies are being tested for TGCTs. They work by targeting the CSF-1 receptor. These drugs are classified as CSF-1R inhibitors. Some of these medicines can be taken by mouth. Others are given with an IV or an injection into your affected joint.
Drugs in testing for TGCTs include:
AMB-05X
Emactuzumab
Pimicotinib
Vimseltinib
Some of these medicines are already showing promise in clinical studies. For example, a phase III trial of vimseltinib in people with TGCTs for which surgery wasn’t a good option found that 40% had a good response to treatment. They also were able to function better with less symptoms.
Tenosynovial Giant Cell Tumor (TGCT) Outlook
You should recover after surgery to remove a TGCT. Your doctor will monitor you to see how you’re healing. Localized TGCTs are more easily removed than diffuse TGCTs that affect a larger joint or more widespread area. Your doctor will keep watching to see if there are signs you’re developing another TGCT or that your TGCT is coming back. More than half of people will have a TGCT come back. Sometimes they come back in the same place, but they also can happen in a different place.
If your TGCT isn’t going away with surgery or is considered severe, your doctor may suggest you take a targeted therapy. Some people can have their TGCT go away with this treatment, but more often it works only partially. You also could consider enrolling in a clinical trial testing new treatments for TGCT.
Preventing Tenosynovial Giant Cell Tumor (TGCT)
There’s no way to prevent tenosynovial giant cell tumors (TGCT). Researchers haven’t been able to find any risk factors that relate to developing TGCT. That means it doesn’t seem to be related to the genes you carry, your environment, your job, lifestyle, or where you live. It also isn’t related to demographic factors such as your race or age.
Living With Tenosynovial Giant Cell Tumor (TGCT)
TGCTs aren’t life-threatening. But they can cause pain and trouble with your mobility. They also can affect your quality of life. While surgery or treatment can help, TGCTs often will come back. If you have a growth that you think may be TGCT, see your doctor. It’s easier to remove a TGCT when it’s smaller and affects a more limited area.
Questions for Your Doctor About Tenosynovial Giant Cell Tumor (TGCT)
If you have TGCT or you are concerned that a lump or bump you have could be TGCT, see a doctor. Some questions to ask include:
Could I have a tenosynovial giant cell tumor (TGCT)?
What tests do I need?
If it’s a TGCT, will I need surgery?
What about other treatments?
How likely is it that I will get another TGCT or that my TGCT will come back?
Show Sources
Photo Credit: Denis Lyutov/Medical Images
SOURCES:
Cleveland Clinic: “Tenosynovial Giant Cell Tumor,” “Giant Cell Tumors.”
FDA: “FDA approves first therapy for rare joint tumor.”
National Organization for Rare Disorders: “Tenosynovial Giant Cell Tumor.”
Orthopaedics & Traumatology: Surgery & Research: “Localized and diffuse forms of tenosynovial giant cell tumor (formerly giant cell tumor of the tendon sheath and pigmented villonodular synovitis).”
The Lancet: “Vimseltinib versus placebo for tenosynovial giant cell tumour (MOTION): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial.”
