Idiopathic chronic gout, left knee, with tophus (tophi)

This code signifies a diagnosis of chronic gout where the underlying cause is unknown (idiopathic), specifically affecting the left knee. A key feature is the presence of tophi, which are deposits of uric acid crystals that form visible lumps under the skin or in joints, indicating advanced or poorly controlled gout.

Use this code when documentation clearly states idiopathic chronic gout involving the left knee and explicitly mentions the presence of tophi. This typically applies to patients with a long-standing history of gout, recurrent flares, and physical examination or imaging findings confirming tophaceous deposits in the specified joint.

• Ensure the documentation specifies "idiopathic" and "chronic" gout, as well as the laterality (left knee) and the presence of tophi.
• Do not use this code for acute gout flares or gout without tophi; separate codes exist for those presentations.
• Verify that the documentation explicitly links the tophi to the left knee, not just a general mention of tophi elsewhere.