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

This code signifies a chronic inflammatory arthritis of the left knee caused by a medication, characterized by the presence of urate crystal deposits (tophi) within or around the joint. The drug-induced nature differentiates it from primary gout, and the chronicity implies persistent or recurrent symptoms.

Apply this code when documentation clearly states chronic gout of the left knee, explicitly links it to a specific drug (e.g., diuretics, aspirin), and notes the presence of tophi. This diagnosis typically follows a history of drug exposure and clinical findings consistent with chronic gouty arthritis.

• Always identify the specific drug causing the gout and code it as an adverse effect (T36-T50 with 5th or 6th character 5).
• Ensure documentation specifies "chronic" gout; acute drug-induced gout would be coded differently.
• Verify the laterality (left knee) and the presence of tophi are explicitly stated in the medical record.