What is Pigmented Villonodular Synovitis?

Pigmented villonodular synovitis is a condition which affects the synovial membrane which surrounds the joints. This condition is most commonly seen in the knee, although it can arise in joints such as the hip and hands as well. The cause is not known; there does not appear to be a genetic component, and there are no obvious risk factors which could provide clues as to why some people develop pigmented villonodular synovitis.

In someone with this condition, benign growths appear in the synovial membrane. This leads to inflammation and swelling as fluid builds up. The joint may become stiff and difficult to move, and the patient often experiences pain in the joint. The swelling can have a very rapid onset, which can complicate diagnosis, as it may look like the result of a strain or sprain.

There are several diagnostic tools which can be used to identify pigmented villonodular synovitis. A sample of the fluid inside the joint can be analyzed, and the joint can also be examined in a medical imaging study such as an MRI. Palpation of the joint may also provide clues, as a mass can be present, indicating that there are tumors on or around the joint.

In addition to limiting range of movement in a joint and causing pain, pigmented villonodular synovitis can also eat into the surrounding bone, causing lesions. For this reason, it is necessary to treat the condition, preferably before lesions have begun to form. Treatment involves surgery to remove part of the synovial membrane and the overgrowth, restoring the joint to a more normal condition. However, recurrence after surgery is very high, almost 50%. For this reason, some doctors recommend using radiation therapy on the joint to address the cells which are growing too quickly, in the hopes of preventing a return of the excessive growth.

This condition occurs most commonly in men between 20 and 45. Unfortunately, men in this age range are also at risk for joint injuries such as sprains which can complicate a diagnosis of pigmented villonodular synovitis because a doctor may not recognize this condition immediately Hence, it may take several months or even years to realize what is going on. If pigmented villonodular synovitis keeps returning or it has caused severe damage, a surgeon may recommend placement of an artificial joint. Joint replacement is a more invasive and complex procedure and thus is only recommended when it seems like a good option for the patient.