Pigmented Villonodular Synovitis

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Pigmented Villonodular Synovitis (PVNS) is one of two types of benign tumors that arise from the soft connective tissue of joints, called synovial tissue. Synovial tissue lines the tendons, and bursa (fluid filled cushioning pouches or sacs found in spaces between tendons, ligaments and bones) found in the area of joints. Synovial tissues allow smooth gliding of tendons and joints.

PVNS, rare in children and affecting mostly young adults, is considered a locally aggressive tumor of synovium because it may invade the adjacent bones, although this usually does not happen, except when the affected joint is the hip. Any joint can be affected although the tumor occurs most commonly in the knee joint. The hip joint is the second most common location, followed by the small joints of the hand, foot, ankle or elbow. A variant, giant cell tumor of tendon sheath, is a similar synovial tumor that occurs in tendon sheaths.

Although it can be painful, pigmented villonodular synovitis usually does not spread beyond the affected area. It does, however, have a high rate of recurrence after surgery.

The following are the most common symptoms of pigmented villonodular synovitis. However, each child may experience symptoms differently. Symptoms can depend on the size and location of the tumor. Symptoms may include:

  • Swelling of a joint (usually painless)
  • Joint effusion (fluid, usually bloody), in the joint
  • Pain (sometimes)
  • Sometimes limping or difficulty using legs, arms, hands or feet.

  • The symptoms of PVNS may resemble other conditions. Always consult your child's physician for a diagnosis.

    For unknown reasons, some or all of the synovial lining tissue of a joint occasionally undergoes a change and becomes diseased, wherein the joint lining tissue becomes thick and overgrown and accumulates a rust-colored, iron pigment known as hemosiderin. Strange, foamy cells and large (so-called "giant") cells with many nuclei also appear. The overgrowth of the joint lining tissue can occur diffusely throughout a joint by way of a generalized thickening of the entire lining membrane, or a localized area of synovial membrane can overgrow and form a discrete nodule (tissue mass) that remains attached to the rest of the internal joint lining by way of a stalk. While this disease process does involve abnormal tissue growth, it is uniformly benign and has not been known to metastasize as do malignant growths. PVNS can be considered a benign, "neoplastic" (tumor growth) process, with some varieties being more aggressive in their growth and thus harder to treat, and other varieties being less aggressive in their growth and thus easier to treat.

    In addition to a complete medical history and physical examination, your child will likely undergo one or more of the following tests:

  • X-rays - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film. Magnetic Resonance Imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body. This test can be used alone to diagnose pigmented villonodular synovitis.
  • Arthography - a special x-ray of the affected joint that involves the injection of a radiopaque substance directly into the affected area. Often times, PVNS is first suspected when the joint is aspirated prior to the injection of the radiopaque contrast material because the aspirated joint fluid will contain old, dark blood, which is a sign of PVNS. MRI has, however, largely replaced the need for arthrography, but it is still sometimes used.

  • The exact treatment for pigmented villonodular synovitis varies from child to child, usually depending on :
    • your child's age, overall health, and medical history
    • extent of the disease and whether it is causing pain
    • whether the tumor has invaded the bone
    • your child's tolerance for specific medications, procedures, or therapies
    • how your child's physician expects the disease may progress
    • your opinion or preference
    Since PVNS can continue to grow and invade the bone, the treatment of choice is usually an operation called a synovectomy, in which the affected synovial tissue is surgically removed.

    There is a high rate of recurrence, however, after this operation is performed, so your child's doctor may also recommend radiotherapy if it recurs. This has been used successfully to control recurrence of PVNS, but is generally avoided in children because of growth issues and the concern about radiation associated malignancy later in life.

    Patients who do develop recurrence usually experience minimal symptoms. As long as the bones remain unaffected, your child's doctor may recommend observation alone and will want to monitor your child's condition at routine intervals.


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