ICD-10 Code M05.49 – Rheumatoid myopathy with rheumatoid arthritis of multiple sites (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.49 – Rheumatoid myopathy with rheumatoid arthritis of multiple sites
What it is
This code identifies rheumatoid arthritis affecting multiple sites with associated muscle involvement, or myopathy. Use it when the record links rheumatoid disease to weakness or other muscle disorder findings.
Clinical signs
Clinical features may include inflammatory joint pain, swelling, stiffness, and reduced mobility in more than one site. Muscle weakness or myopathic changes should be documented; clinical features vary, so refer to documentation.
When to use this code
Use M05.49 when the provider documents rheumatoid arthritis with rheumatoid myopathy and involvement of multiple sites. This supports coding when the chart clearly connects the muscle condition to rheumatoid disease. Check documentation if the record does not specify the sites or the myopathy link.
Do not use for
Do not use this code for rheumatoid arthritis without documented myopathy, or for isolated muscle pain without a rheumatoid cause. If the arthritis is not in multiple sites, select the more specific documented code.
Coding tip
Confirm both the rheumatoid arthritis diagnosis and the muscle involvement in the provider note before assigning M05.49.