ICD-10 Code M05.79 – Rheumatoid arthritis with rheumatoid factor of multiple sites without organ or systems involvement (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.79 – Rheumatoid arthritis with rheumatoid factor of multiple sites without organ or systems involvement
What it is
This code identifies rheumatoid arthritis with a positive rheumatoid factor affecting multiple joints, without documented involvement of organs or body systems outside the joints. Use it when the record supports seropositive RA at more than one site.
Clinical signs
Common findings include chronic inflammatory joint pain, swelling, stiffness, and reduced range of motion in multiple joints. Clinical features vary; refer to documentation for the affected sites and confirm rheumatoid factor positivity.
When to use this code
Use this code when the provider documents rheumatoid arthritis with rheumatoid factor and specifies multiple sites, but does not document extra-articular organ or system involvement. It is appropriate for seropositive RA affecting several joints, such as hands, wrists, or feet, when no systemic complications are recorded.
Do not use for
Do not use this code if rheumatoid factor is not documented, if the arthritis is limited to one site, or if organ or system involvement is reported. Check documentation for more specific RA codes when extra-articular disease is present.
Coding tip
Verify both elements: rheumatoid factor positivity and multiple-site joint involvement before assigning M05.79.