This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Musculoskeletal Radiology, Subject name: Radiology
Pigmented Villonodular synovitis most commonly involves? 
Select and explain. 
A. Shoulder, B. Knee, C. Hip, D. Ankle
B: Knee
Answer: B: Knee 
Explanation: Pigmented villonodular synovitis (PVNS) is a benign proliferative condition affecting synol membranes of joints, bursae or tendons resulting from synol proliferation with villous and nodular projections and haemosiderin deposition. PVNS is most commonly mono aicular mainly involving Knee joint