Villonodular synovitis (pigmented), unspecified knee

This code describes pigmented villonodular synovitis (PVNS) affecting an unspecified knee. PVNS is a rare, benign, proliferative disorder of the synovial membrane, characterized by villous and nodular growth with hemosiderin deposition, leading to joint pain, swelling, and limited range of motion.

Use this code when documentation confirms a diagnosis of pigmented villonodular synovitis in a patient's knee, and the specific knee (right or left) is not documented or is unknown. This code is appropriate when the physician's notes explicitly state "PVNS of the knee, unspecified."

• Avoid using this code if the laterality (right or left knee) is specified in the medical record; instead, choose the more specific code (M12.261 or M12.262).
• Ensure the documentation clearly identifies the condition as pigmented villonodular synovitis, not just general synovitis.
• Consider any associated symptoms or complications, such as effusion or pain, and code them additionally if supported by documentation.