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, most commonly in the knees. PVNS is also called diffuse PVNS, pigmented tenosynovitis, or diffuse giant cell tumor.

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 break down.

Treatment usually involves surgical excision of the tumor. While it can recur after surgery, removal of the thickened area or radiation therapy may be the most effective ways to alleviate symptoms and prevent serious bone damage.

Pigmented villonodular synovitis diagnosis
Verywell / Cindy Chung 

Symptoms

This condition typically affects adults before age 50, and it has a tendency to grow rapidly, to extend, and to recur in the same location after treatment. PVNS does not commonly spread, as it tends to expand rather than affect far away areas in the body.

The condition can develop suddenly and may manifest with rapid swelling of the affected joint. You may feel mild to moderate pain or discomfort, and the thickening in your joint can interfere with your ability to move. The area may appear red and it can be tender to the touch. Sometimes pain and discomfort may worsen with movement. 

PVNS does not usually affect more than one joint, although that can occur. 

Complications 

Bone, ligament, and tendon breakdown is the late stage consequence of PVNS. As these joint structures begin to break down, the process may not initially cause any symptoms at all. However, joint instability or fractures can result, which may produce severe pain and even the inability to walk.

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

Causes

PVNS is caused by overgrowth and thickening of the synovium. This is also described as hypertrophy, which is an overgrowth of healthy tissue.

Synovium, which is also called synovial lining, is a thin capsule that produces and encloses a lubricating fluid called synovial fluid. All moving joints in the body have synovium, which protects the bones, ligaments, tendons, and muscles as they move within the joint. 

The thickened synovial lining of PVNS results in the visible swelling, can interfere with movement, and may grow into and destroy nearby bone. 

Triggers

The reason that a person develops PVNS is not known. The synovial tissue overgrowth is characterized by the presence of giant cells and macrophages.

Giant cells are typically associated with the healing of damaged tissue. And macrophages are usually a sign of infection (or past infection). This has led experts to suggest 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. 

There have also been a number of genetic mutations (alterations in a person’s genetic code) identified in association with PVNS. These mutations may be present within the tumor, but are not seen in other cells throughout the body. This suggests that PVNS is probably not an inherited condition, but that the mutations may occur as a result of some environmental factor, which could indeed be joint damage.

Diagnosis

This type of tumor can be evaluated with a physical examination, imaging studies, and a biopsy. There are two types of PVNS, described as localized and diffuse. As these names suggest, the localized form is not as widespread as the diffuse form. However, it’s also important to note that the localized form may advance and change into the diffuse form, spreading further in the joint. 

If you have symptoms of PVNS, you may have the following evaluation: 

Physical examination: Your doctor will examine your joint and assess its appearance, your physical movements, and whether the joint is tender to the touch. The next steps in your assessment depend on your physical examination. 

Imaging studies: You may need an X-ray, magnetic resonance imaging (MRI) or a bone scan so your medical team 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.

Needle aspiration: The fluid within the synovial capsule can be sampled with a needle. This is a minimally invasive test that should take less than half an hour. This fluid can then be examined for alterations in appearance or composition. 

Biopsy: A biopsy is a more invasive procedure than a needle aspiration because synovial tissue is actually removed. However, a biopsy may be more helpful in identifying the features of PVNS. 

This tumor is a giant cell tumor and biopsy sample of the synovial tissue can be examined under a microscope to assess for the presence of giant cells or other changes. 

Treatment

You can take over-the-counter or prescription-strength pain medication or anti-inflammatory medication to reduce your swelling and discomfort. However, if the tumor is growing, causing substantial pain, or interfering with your movements, you may need more serious intervention, such as surgery or radiation. 

Surgery: The tumor can take up space and may encroach on the bones in the affected joint, 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, surgery is only a temporary solution, and the tumor may grow back. If the tumor is destructive to the joint structures, surgical repair of the affected structures within the joint (such as the tendons or ligaments), in addition to tumor resection, may be necessary as well. 

Radiation: Sometimes radiation therapy is used to shrink the tumor. This can be safe and effective, but, as with surgery, radiation therapy may need to be repeated if the tumor returns. 

While radiation can help you avoid a surgical incision, 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 and as a tumor because it has features of both. 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 you do need to give it attention (even if the symptoms are mild) to avoid the potential complications.

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