Pigmented Villonodular Synovitis (PVNS) is a rare, benign proliferative disorder of the synovium, which is a thin layer of tissue that lines the joints and tendon sheaths. PVNS typically affects the knee, but it can also occur in other joints such as the hip, ankle, or shoulder. Symptoms of PVNS can include joint pain, swelling, stiffness, and sometimes limited range of motion. Treatment options may include surgery, medications, or other interventions depending on the severity of the condition.