Q.My husband has been diagnosed with pigmented villonodular synovitis. He has had surgery on his right knee once and left knee twice. His left knee continues to be very painful and swells following exercise. Any information would be appreciated. He is 49 years old.
A.Pigmented villonodular synovitis (PVNS) is a condition that affects the synovium, a layer of tissue within the joints that secretes fluid for nutrition to the joint and aids in lubrication. Unfortunately, in PVNS, the synovium gets out of control, becoming thickened and more abundant. The synovium in this disease becomes pigmented with a substance called hemosiderin, which gives it a characteristic reddish-brown color.
A.The cause of PVNS is unclear. In most cases, there is no history of direct injury. Patients with PVNS typically begin having symptoms in their 20s and 30s. It typically affects one joint rather than multiple joints. The knee is the most common joint affected, followed by the hip.
Upon physical examination, I usually find good range of motion of the joint. Fluid within the joint is quite common, and when this fluid is removed, it often has a characteristic brownish appearance from the hemosiderin. On X-ray, a joint affected by PVNS shows only mild narrowing. This is in contrast to a joint affected by arthritis, which typically shows significant narrowing. Magnetic resonance imaging (MRI) is very helpful in the diagnosis of PVMS. Eroded areas of the bone as well as cyst formation can be seen and can affect both sides of the joint.