Pigmented Villonodular Synovitis (PVNS)

*Pigmented villonodular synovitis (PVNS) facts written by Charles P. Davis, MD, PhD

• Pigmented villonodular synovitis (PVNS) is a disease where the tissue lining the joints and tendons grow abnormally to produce a noncancerous mass or tumor. There are two types: local (nodular) and diffuse. Local involves one area of the joint lining while diffuse involves the entire lining of the joint. It most often affects the knee joint.
• PVNS symptoms and signs may include swelling, joint effusion, pain, limited joint movement, and/or locking of the joint; some individuals experience joint destruction.
• The exact cause of PVNS is unknown; researchers speculate it may be related to arthritis, joint trauma, or specific genetic changes.
• Medical professionals diagnose PVNS by taking X-rays, an MRI, and CT scans; sometimes it may be necessary to perform a joint aspiration and/or biopsy.
• Physicians use surgery to remove abnormal tissue from the joint; if surgery cannot be done or if the disease recurs, radiation therapy may be necessary.
• PVNS is a rare disease (44/100,000 people for local PVNS and 11/100,000 people for diffuse PVNS).

Pigmented villonodular synovitis (PVNS) is a disease in which the tissue lining the joints and tendons in the body (synovium) grows abnormally. It is characterized by a noncancerous mass or tumor. There are two types of PVNS: the local or nodular form (where the tumor involves the tendons that support the joint, or in one area of the joint) and the diffuse form (where the entire lining of the joint is involved). Symptoms might include: pain, limitation of movement, and locking of the joint. In some cases, the normal joint structure can be destroyed. The knee is most commonly affected by this condition, though it can occur in other joints such as the hip, shoulder, elbow, ankle, wrist, and rarely the jaw. The average age of diagnosis for this condition is 35 years. The cause of PVNS is unknown. Treatment involves surgery to remove the tumor and damaged portions of the synovium.

The exact cause of pigmented villonodular synovitis (PVNS) is unknown. Some doctors believe that it is similar to arthritis, arising from swelling (inflammation) of the joint tissue. Others believe it develops like a tumor, caused by cells growing and multiplying more quickly than usual. The association between a history of trauma and the development of PVNS is unclear. One study found that 56% of individuals with PVNS had a history of previous trauma, while other studies have found a much lower incidence.

There have been studies suggesting that PVNS could be caused by specific genetic changes in the cells lining the joint. More studies are needed to research this association.

Pigmented villonodular synovitis (PVNS) is diagnosed via physician examination, imaging studies, and sometimes surgical procedures. Imaging studies commonly used include: X-ray, MRI, and CT scan. MRI findings are diagnostic in more than 95% of patients. CT scan findings are additionally often diagnostic, though they might not show the extent of the disease.

Other methods that might be utilized in the diagnostic process include joint aspiration, in which a needle is used to remove fluid from the joint and a biopsy, in which a small operation is completed to obtain a tissue sample.

Pigmented villonodular synovitis is first treated with surgery to remove as much of the abnormal tissue growth as possible. The type of surgery depends on the location and extent of the disease within the joint. Radiation therapy is sometimes used to treat this condition if surgery is not an option, or if the condition returns (recurs) after an initial surgery.

Pigmented villonodular synovitis (PVNS) is considered rare. Estimates of prevalence may vary depending on the type of PVNS (localized or diffuse). According to a recently published study based on registry data in Denmark, the prevalence in 2012 was 44 per 100,000 people for localized PVNS, and 11 per 100,000 people for diffuse PVNS. This means that PVNS may occur in about 5-6 people out of 10,000 people. We are not aware of recent prevalence estimates of PVNS in the United States.