Villonodular synovitis is a benign, proliferative (i.e. growing) disease of the so-called synovia, i.e. the synovial fluid and synovial membrane. This synovial fluid fills the joint space, for example the knee joint, where it acts as a lubricant and supplies the cartilage structures in the joint.
Villonodular synovitis can occur in various forms. The first is a rather limited, nodular form called nodular synovitis. It affects only a narrowly defined area and is usually easy to treat.
On the other hand in a rather diffuse form of villonodular synovitis, the villous type. The entire joint is usually affected. It tends to spread more widely and often reoccurs after surgery. If pigmentation is also present in the joint area, it is known as pigmented villonodular synovitis (PVNS).
Causes
The causes of villonodular synovitis are still completely unclear. It may be related to the frequent occurrence of bloody joint effusions and previous joint inflammation. Mostly the large joints are affected, i.e. mainly the knee and hip joint, but sometimes also the shoulder joint.
Overall, it is still unclear whether the development is more like a tumor or other chronic inflammatory diseases, such as arthritis. Villonodular synovitis is one of the most common synovial diseases. It mostly affects people aged 30-40 years. Villonodular synovitis is a tumorous clinical picture, but is benign.
Symptoms
Symptoms vary depending on the underlying type of disease. In the chronic, diffuse form, swelling and pain in the affected joint usually occur over years. The swelling can become very severe due to an increased production of synovial fluid.
In addition, there may also be pain in the joint area and in the area of the adjacent extremity. Due to these symptoms, confusion with other diseases, for example of the vessels, is possible. In addition, the symptoms are similar to chronic inflammatory diseases, such as arthritis.
In the nodular type of the disease, the most striking feature is often a restriction of joint movement. This is due to the fact that the rather nodular and firm new formation is trapped during movement and thus causes discomfort. However, pain and swelling are often added. A typical feature of villonodular synovitis, however, is that, in contrast to many degenerative diseases, only one joint is usually affected. In both variants of villonodular synovitis, it is possible that the symptoms occur only in phases and increase or decrease over time.