An Overview of Pigmented Villonodular Synovitis (PVNS)

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Pigmented villonodular synovitis (PVNS) is a rare type of growth that can involve joints throughout the body, but occurs most commonly in the knees. PVNS is typically categorized as localized or diffuse. It is also called tenosynovial giant cell tumor when it occurs in a tendon.

While it is often described as a tumor or a neoplasm, it is not usually cancerous. This growth may cause pain or swelling of a joint, and it can cause the nearby bones and tendons to degenerate.

Treatment usually involves surgical excision of the affected area. While it can recur after surgery, removal of the thickened area may be the most effective way to alleviate symptoms and prevent further damage. In some cases, radiation therapy can be added as a treatment.

Pigmented villonodular synovitis
Verywell / Cindy Chung 

Symptoms

This condition typically affects adults before age 50, and it can have a tendency to grow or recur in the same location after treatment. PVNS typically affects only one joint, but it can affect more than one joint in some cases. It does not tend to spread to far-away areas in the body.

The condition can manifest with swelling of the affected joint. You may feel mild to moderate pain or discomfort, and in some cases PVNS in the joint can interfere with your ability to move. Sometimes pain and discomfort may worsen with movement. 

Complications 

Joint degeneration, including bone, ligament, and tendon breakdown, can be a late-stage consequence of PVNS. Initially, the process may not cause any symptoms at all. However, severe degeneration of the joint can result in instability or severe pain and even the inability to walk.

It is important to seek medical attention if you have a persistently swollen joint, even if you aren’t experiencing significant discomfort.

Causes

PVNS is caused by overgrowth and thickening of the synovium. Synovium, which is also called synovial lining, is a thin capsule that encloses the joint and produces a lubricating fluid called synovial fluid. All moving joints in the body have synovium, which reduces friction in the joint structures as the joint moves. 

The abnormal synovial lining caused by PVNS results in joint swelling, can sometimes interfere with movement, and may grow into and destroy nearby joint structures, including bone in severe cases. 

Triggers

The reason that a person develops PVNS is not known. Experts have suggested that PVNS could be induced by wear and tear or injuries of the affected joint, although there may be genetic or environmental components as well. A number of genetic abnormalities have been identified within PVNS tumors.

Diagnosis

This type of tumor can be evaluated based on your history, a physical examination, imaging studies, and a biopsy. If you have symptoms of PVNS, you may have one or more of the following evaluations: 

Physical examination: Your doctor will examine your joint and assess its appearance, your physical movements, and whether the joint is swollen or tender to the touch. 

Imaging studies: You may need an X-ray or magnetic resonance imaging (MRI) so your heath care provider can get a good look at your joint to determine the cause of your symptoms. 

With PVNS, the synovium can appear thick, swollen, or enlarged on imaging studies.

Joint aspiration: The fluid within the joint can be sampled with a needle. This is a minimally invasive test that should take a few minutes. This fluid can then be examined for alterations in appearance or composition. 

Biopsy: A biopsy may provide more information in identifying the features of PVNS, because synovial tissue is actually sampled. The biopsy sample of the synovial tissue can be examined under a microscope to assess for the presence of particular types of cells or other changes consistent with PVNS. 

Treatment

Once you have a diagnosis of PVNS, over-the-counter or prescription-strength anti-inflammatory medication may be helpful to reduce your swelling and discomfort. Because the tumor tends to grow and can cause substantial degeneration of the joint, your doctor may recommend interventions such as as surgery or radiation. 

Surgery: The tumor can take up space and, as it grows, cause degeneration in the joint. It may also encroach on the bones, potentially causing bone degeneration. For this reason, your doctor may recommend surgical removal of the growth as a way to avoid damage to your joint. 

In some instances, the tumor may grow back after the surgery. If the tumor involves other structures besides the lining of the joint, surgical repair of the affected structures (such as the tendons), in addition to tumor resection, may also be necessary. 

Radiation: Sometimes radiation therapy is used to shrink the tumor. Radiation therapy can be effective in reducing the risk of recurrence in some cases, but, as with surgery, there can be side effects of radiation, so the decision about ideal treatment requires a careful and individualized approach.

A Word From Verywell

PVNS has been described as a growth or a tumor in the lining of the joint. While it is accurately labeled as a tumor, it is not cancer and it is not typically life-threatening.

However, PVNS can be destructive to your joints, so if you have been given this diagnosis, you do need to give it attention (even if the symptoms are mild) to avoid the potential complications associated with its progression.

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