Drug-induced chronic gout, right knee, with tophus (tophi)

This code signifies a chronic inflammatory arthritis of the right knee caused by medication, characterized by the presence of tophi. Tophi are deposits of monosodium urate crystals that form under the skin or in other tissues, indicating long-standing, uncontrolled hyperuricemia.

Apply this code when documentation clearly indicates chronic gout in the right knee, explicitly attributed to a drug, and notes the presence of tophaceous deposits. This typically occurs in patients with a history of medication use (e.g., diuretics, aspirin) contributing to hyperuricemia and visible or palpable tophi.

• Ensure documentation specifies "drug-induced" and not just "secondary" gout.
• Verify the laterality (right knee) and the presence of tophi are clearly stated.
• Sequence this code first if it is the primary reason for the encounter, followed by codes for the specific drug causing the condition (T36-T50 with 5th or 6th character indicating adverse effect).