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Pigmented Villonodular Synovitis (PVNS)

Pigmented villonodular synovitis (PVNS) is a painful health issue that happens when the soft tissue lining of a joint grows out of control. It’s not life-threatening, but it can get worse over time and interfere with your ability to move the joint freely.

Doctors usually treat PVNS with surgery.

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What Is PVNS?

Doctors define PVNS as a condition where the lining of a joint or tendon (the synovium) grows too thick and causes problems. 

This overgrowth of synovium creates an abnormal mass of tissue or tumor. This tumor is benign (noncancerous) and doesn’t spread to other parts of your body. But it does get worse with time, destroying bone and interfering with your quality of life. 

PVNS also causes swelling. In a normal joint, the synovium makes fluid that helps the joint move smoothly back and forth. But if you have PVNS, the synovium produces too much fluid, which causes the joint to swell painfully.

The knee is the affected joint in about 80% of people with PVNS, according to the American Academy of Orthopaedic Surgeons. PVNS also can happen in the hips, ankles, shoulders, and elbows but usually only affects the joint on one side of the body.

How common is PVNS?

PVNS is extremely rare. Fewer than two people per million are diagnosed with PVNS in the U.S. each year, according to the National Center for Biotechnology Information

PVNS can occur at any age, but it most frequently happens in people ages 20 to 50. The condition may occur slightly more often in men.

What are the types of PVNS?

There are two types of PVNS:

  • Diffuse PVNS happens when the tumor spreads through the entire joint. This type of PVNS is faster growing, more aggressive, and can be more difficult to treat than localized PVNS.
  • Localized PVNS occurs if the tumor stays in one part of the joint. PVNS is also considered localized if it only involves the tendons that support the joint. Localized PVNS is typically easier to treat and responds well to treatment.

What causes PVNS?

Doctors don’t know what causes PVNS. Researchers have found some genetic changes identified with PVNS, but what causes the changes isn’t clear.

What are PVNS risk factors and complications?

Doctors are still learning about possible risk factors for PVNS. They do know that it can cause bone deterioration and other complications if not treated.

PVNS risk factors

There are no known risk factors for PVNS. It doesn’t appear to run in families, and there are no consistent causes — like sports injuries or doing a physical job — among people with PVNS.

Complications of PVNS

PVNS is a progressive disease. Left untreated, PVNS will slowly get worse and can lead to bone damage, arthritis, and limited range of movement in the affected joint.

PVNS isn't life-threatening and doesn’t spread beyond the affected joint. But it can affect your ability to move and your quality of life.

How can I prevent PVNS?

There's no known way to prevent PVNS.

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What Are the Signs and Symptoms of PVNS?

You may not notice PVNS problems at first, or you may mistake the symptoms for another problem, like arthritis.

Signs of PVNS include:

  • Hemarthrosis, or bleeding inside a joint, without any noticeable injury. The area around the joint may look bruised or discolored.  
  • Instability in the joint.
  • Popping, locking, or catching when you move the joint.
  • Stiffness and swelling in a joint, most often the knee.
  • Symptoms that come and go and get worse as time goes by.

When should I see a doctor about my PVNS symptoms?

You should see an orthopaedic specialist if you have:

  • Pain in a joint that comes and goes.
  • Pain in one knee only.
  • Swelling or bruising of a joint with no injury.
  • Unexplained joint pain.

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How Do You Diagnose PVNS?

You should see an orthopaedic specialist for PVNS. Because PVNS has similar symptoms to other joint problems, your doctor will want to rule out other more common conditions, like arthritis.

What to expect during your visit

Your doctor will ask you about your medical history, symptoms, and any joint conditions that run in your family. They'll do a physical exam and, if they suspect PVNS, will order imaging tests and other lab work. 

Tests to diagnose PVNS

Your doctor may run the following tests to diagnose PVNS:

  • Biopsy. Your doctor will take a small tissue sample from the tumor to examine under a microscope to confirm the PVNS diagnosis.
  • Joint aspiration. Your doctor will remove fluid from the joint with a syringe and send it to a lab for analysis. If you have PVNS, the fluid may look bloody.
  • MRI. This imagining test shows clear pictures of soft tissue like organs, blood vessels, and tendons. If you have localized PVNS, it may show as a mass. If you have diffuse PVNS, it may show thickening of the entire joint lining or a mass with bone and cartilage damage.
  • X-ray. If PVNS is in the early stages (where it hasn’t damaged the bone), the tumor may not show up on an x-ray. However, an x-ray can help your doctor rule out arthritis and other health issues.

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How Do You Treat PVNS?

Because PVNS will get worse with time, it’s important to treat it as soon as possible. Your doctor will talk to you about possible treatment options.

Surgery for PVNS

Doctors usually recommend surgery for PVNS because the tumor can grow very large and destroy healthy bone. Surgery will remove the tumor and any damaged parts of the joint lining. Your doctor will also repair any damaged tendons during the surgery.

There are several types of surgery for PVNS:

  • Arthroscopy. Doctors use this method for both localized and diffuse PVNS, if possible, as it leads to a quicker recovery time. Surgeons make a few small cuts around the joint, then insert a small camera that displays images on a monitor. The surgeon uses these images to guide tiny surgical instruments and remove diseased tissue through a thin tube.  
  • Open surgery. If PVNS affects both the front and back of the knee, surgeons will need to remove the entire joint lining with the tumor. That way, the tumor won’t come back. The larger incision of traditional open surgery allows the surgeon better access to remove the whole tumor and joint lining.
  • Open surgery combined with arthroscopic surgery. Depending on where the tumor is, doctors may combine surgery methods. If it’s in the back of the knee, open surgery can remove the tumor. They may still be able to use arthroscopic surgery to remove the front joint lining, making for a quicker recovery.
  • Total joint replacement. If PVNS has caused major joint destruction, replacing it with an artificial joint may be the best option. Doctors replace parts of the damaged joint with metal, plastic, or ceramic parts.

Recovery time from PVNS surgery

How long it takes to recover from PVNS surgery depends on what procedure you have. You'll need some form of physical therapy to get back to normal. A physical therapist can show you exercises to regain strength and range of motion, and how to minimize stiffness.

It may help to use crutches after surgery, to keep your weight off your sore knee. An over-the-counter anti-inflammatory, such as ibuprofen, aspirin, or naproxen, can help ease pain and swelling after surgery. 

It may be several months before you can return to normal activity, especially if you had open surgery for diffuse PVNS. 

Radiation therapy to treat PVNS

If you have diffuse PVNS and surgery wasn’t successful, your doctor may recommend radiation therapy. Radiation therapy can often shrink tumors (even noncancerous ones) and give you relief from pain. Doctors sometimes use it after surgery to lower the risk of the tumor coming back.

Doctors can apply radiation therapy through an external beam directed at the problem joint. Or they may opt for a newer method — intra-articular radiation — where they inject radioactive fluid into the joint to shrink the tumor.

Drug therapy to treat PVNS

Researchers are studying medicines for the treatment of PVNS. These drugs target a specific protein in the joint lining. Your doctor can discuss drug therapy with you, and whether you're a good candidate.

How effective is treatment?

There's little chance of localized PVNS coming back after surgery.

But if you had diffuse PVNS, you'll need to see your doctor for follow-up visits for several years after surgery. Even with treatment, including total joint replacement, PVNS can come back over time. The recurrence rate for diffuse PVNS is between 10% and 30%. 

Your doctor may order tests, like an MRI, at these follow-up visits to see if the tumor has regrown. 

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