ICD-10 Code M05.161 – Rheumatoid lung disease with rheumatoid arthritis of right knee (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.161 – Rheumatoid lung disease with rheumatoid arthritis of right knee
What it is
This code identifies rheumatoid arthritis affecting the right knee together with rheumatoid lung disease. Use it when the record clearly links both the joint disease and the pulmonary manifestation to rheumatoid arthritis.
Clinical signs
Findings may include chronic inflammatory arthritis of the right knee plus documented rheumatoid lung involvement, such as interstitial lung disease, nodules, pleural disease, or other rheumatoid pulmonary manifestations. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents rheumatoid arthritis with right knee involvement and specifically states rheumatoid lung disease. The diagnosis should connect the lung condition to the rheumatoid disease, not just list both separately. If laterality or the pulmonary manifestation is unclear, check documentation.
Do not use for
Do not use this code for rheumatoid arthritis without lung disease, or for lung disease not attributed to rheumatoid arthritis. If the affected knee is not the right knee, choose the appropriate laterality code.
Coding tip
Confirm both laterality and the rheumatoid lung complication in the assessment or problem list before assigning M05.161.