A person outside holding their knee.
Tenosynovial giant cell tumors often affect the joints and tendons.

What is a Tenosynovial Giant Cell Tumor?

Swelling in your joints should not be ignored, even if it is mild. Joint pain could be more than wear and tear arthritis—it may be a symptom of a rarer condition called tenosynovial giant cell tumor.

With a median age of 30 at diagnosis, tenosynovial giant cell tumors can affect joints of those who are young to middle-aged adults. Left untreated, this condition may lead to severe disability.

Tenosynovial Giant Cell Tumor Explained

Tenosynovial giant cell tumors are rare, benign tumors that cause areas within joints to thicken and overgrow. Though these tumors are not cancerous, nor do they spread to other parts of the body, but they can create additional health complications.

As tenosynovial giant cell tumors grow, they may damage or destroy surrounding bone and tissue, creating debilitating issues. These tumors can occur anywhere bones join together, potentially affecting any body part. It’s imperative to see a physician when you experience symptoms to stop tenosynovial giant cell tumors early.

Where Do They Grow?

These types of tumors occur in the synovium, bursae, and tendon sheath:

  • Synovium is the layer of tissue or membrane covering the inner surface of the joints, bursae, and tendon sheaths.
  • Bursae are small sacs filled with fluid around the joints. They reduce friction by cushioning bones, tendons, and muscles during movement.
  • Tendons are the tissues connecting muscle to bone. The tendon sheath is the membrane covering a tendon.

What Are the Subtypes?

This condition can affect large or small joints. Tenosynovial giant cell tumor subtypes can be classified as localized (nodular) or diffuse type.

Localized tenosynovial giant cell tumors are commonly found in extremities, such as the joints in the hands and feet. Diffuse tumors affect larger joints, such as the knee, which is the most common location for tenosynovial giant cell tumors.

Symptoms of Tenosynovial Giant Cell Tumors

Patient symptoms are often unrecognized as they may not seem severe enough to warrant a medical opinion. Diffuse tumors tend to have more severe symptoms, where localized tumors present with milder symptoms. As these tumors do not metastasize, symptoms of the condition are common in one area or joint.

Some symptoms associated with tenosynovial giant cell tumors are:

  • Pain, swelling, or stiffness in a particular area or joint
  • Limitation of joint movement
  • Locking or catching sensation when moving the joint
  • Inflamed and thickened synovium

Due to the rareness of this condition and its vague symptoms, there may be a delay between when symptoms start and when a diagnosis is reached—all the more reason to see your doctor early.

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Tenosynovial Giant Cell Tumor Warning Signs

This condition has ambiguous symptoms that may be dismissed by patients until the tumor grows and causes more damage. The signs vary depending on the location and subtype of the tumor. In general, sudden inexplicable swelling around a joint or joints with recurrent inflammation are a sign that you should see a doctor. It may indicate another type of joint issue, but it is best to have a professional look at your affected joint as early as possible before the tumor grows and causes more damage.

What Causes Tenosynovial Giant Cell Tumors?

Research tells us that a small number of cells that make up these tumors carry a specific chromosomal translocation. That is to say a region of an affected person’s chromosomes breaks off and rearranges itself, shifting their genetic material and creating altered chromosomes. Currently, there is no known cause for translocation of these chromosomes—it seems to happen randomly without reason.

Treatment Options

As with any medical treatment, physicians collect as much data as possible about the location, subtype and size of the tumor, and information about the patient and their overall health. This information defines the approach for treating tenosynovial giant cell tumors.


Surgery is the main treatment of this condition. It’s generally successful with a good prognosis for patients. As these tumors are benign and generally limited to one location, surgery is the best option for treatment, typically using a partial synovectomy. The goal of this surgery is to remove all of the diseased synovium, however, it is not possible in all areas, such as the hip. Surgeons do their best to take as much of the tumor out without impacting surrounding tissues and bones. Even with surgery, there is a risk of recurrence for tenosynovial giant cell tumors.

In very rare cases, surgery may require joint replacement or amputation. These more involved procedures are suggested by physicians when a patient’s pain is not just tumor-related, but when they have a lot of mechanical pain due to joint destruction.

Radiation Therapy

In cases where the tumor cannot be completely removed by surgery, doctors may use radiation therapy as an adjunct treatment. Radiation therapy uses powerful energy beams to shrink a tumor or stop it from growing. In particular, intra-articular radiation for tenosynovial giant cell tumors has proven successful.

Tyrosine Kinase Inhibitors

In 2019, the U.S. Food and Drug Administration approved the tyrosine kinase inhibitor. It treats adult patients with tenosynovial giant cell tumor symptoms associated with severe disease or functional limitations that are not likely to be improved with surgery.

If tenosynovial giant cell tumors go untreated or these tumors continually recur, the surrounding tissues or structures may become damaged or degenerate, leading to disability.

Talk to Your Doctor

With joint pain, no matter how minor, patients should consult a doctor and start treatment to alleviate their symptoms and prevent further destruction to other areas. Treating joint pain early may restore your mobility and alleviate other symptoms too.