Idiopathic chronic gout, unspecified knee, with tophus

This code signifies a chronic, idiopathic form of gout affecting an unspecified knee, characterized by the presence of tophi. Tophi are deposits of monosodium urate crystals that accumulate in soft tissues, often around joints, indicating advanced or poorly controlled gout. The "idiopathic" nature implies the cause is unknown or primary.

Use this code when documentation confirms a diagnosis of chronic gout with no identified secondary cause, specifically involving an unspecified knee, and explicitly states the presence of tophaceous deposits. This code is appropriate when the laterality of the affected knee is not specified in the medical record.

• Ensure documentation clearly distinguishes between acute and chronic gout, and specifies "idiopathic."
• Verify the presence of tophi is explicitly documented; do not assume based on chronic gout alone.
• If laterality (right or left knee) is documented, a more specific code should be used instead of this "unspecified" option.