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 grossly unknown. Treatment involves surgery to remove the tumor and damaged portions of the synovium.
Last updated: 4/4/2016
What causes pigmented villonodular synovitis?
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. 
Last updated: 4/5/2016
How might pigmented villonodular synovitis be treated?
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.
Last updated: 4/5/2016
How common is pigmented villonodular synovitis?
Pigmented villonodular synovitis is rare, affecting two in a million people.
Last updated: 11/28/2011
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
Guo-ping Xie Nan Jiang, Chang-xiang Liang, Jian-chun Zeng, Zhi-yuan Chen, Qian Xu, Rui-zhen Qi, Yi-rong Chen, Bin Yu. Pigmented Villonodular Synovitis: A Retrospective Multicenter Study of 237 Cases. PLoS One. March 23, 2015; 10(3):http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370558/.
Mendenhall WM, Mendenhall CM, Reith JD, Scarborough MT, Gibbs CP, Mendenhall NP. Pigmented Villonodular Synovitis. American Journal of Clinical Oncology. 2006; 29:548-550. http://www.ncbi.nlm.nih.gov/pubmed/17148989.
Ravi V, Wang WL, Lewis VO. Treatment of tenosynovial giant cell tumor and pigmented villonodular synovitis. Current Opinion in Oncology. 2011; 23:361-366. http://www.ncbi.nlm.nih.gov/pubmed/21577109. Accessed 11/22/2011.