Radial styloid tenosynovitis [de Quervain]

This code represents an inflammatory condition affecting the tendons and their synovial sheaths along the thumb side of the wrist, specifically the abductor pollicis longus and extensor pollicis brevis tendons. It is commonly known as de Quervain's tenosynovitis, characterized by pain and tenderness over the radial styloid process.

Use this code when documentation clearly indicates a diagnosis of de Quervain's tenosynovitis or radial styloid tenosynovitis. Supporting clinical findings often include a positive Finkelstein's test, localized swelling, and pain with thumb and wrist movement.

• Ensure the documentation specifies the radial styloid or de Quervain's to differentiate from other wrist tenosynovitis.
• Do not confuse with other forms of tenosynovitis affecting different tendons or locations, which have distinct codes.
• Consider laterality if specified (e.g., M65.40 for unspecified, M65.421 for right, M65.422 for left).