Pigmented villonodular synovitis (PVNS) , also known as intra-articular giant-cell tumor of the tendon sheath, is a joint disease characterized by inflammation and overgrowth of the joint lining, becoming benign tumors. It usually affects the hip or knee. It can also occur in the shoulder, ankle, elbow, hand or foot. In PVNS patients, the lining of the joint, called the synovium, becomes swollen and grows foreign bodies. This growth harms the bone next to the joint. The lining also makes extra fluid that can cause swelling and make movement painful, limiting range of motion. PVNS is idiopathic, it doesn't seem to run in families or be caused by certain jobs or activities, although it has been associated with prior injury. Surgery can help, although there is a high reoccurrence rate. Depending on the type of PVNS, localized or diffused, the reoccurrence rate differs with localized being easier to resect generally. If the pain remains then radiation therapy or chemotherapy may help. In the worst cases the joint must be replaced or amputated.