ICD-10 Code M05.412 – Rheumatoid myopathy with rheumatoid arthritis of left shoulder (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M05.412 – Rheumatoid myopathy with rheumatoid arthritis of left shoulder
What it is
This code identifies rheumatoid arthritis affecting the left shoulder with associated rheumatoid myopathy. Use it when the record shows both joint involvement and muscle disease linked to rheumatoid arthritis.
Clinical signs
Typical findings include chronic inflammatory joint symptoms in the left shoulder, such as pain, stiffness, and reduced range of motion. Muscle weakness or myopathic changes may also be documented; clinical features vary, so refer to documentation.
When to use this code
Use this code when the provider documents rheumatoid arthritis of the left shoulder and specifically links rheumatoid myopathy to the same condition. It is appropriate when the left shoulder is the named site, not a different joint or generalized rheumatoid arthritis. Check documentation if laterality or the myopathy link is unclear.
Do not use for
Do not use this code for rheumatoid arthritis without documented myopathy, or for myopathy that is unrelated to rheumatoid disease. Do not assign it when the involved shoulder is not the left side.
Coding tip
Verify both laterality and the provider’s explicit connection between rheumatoid arthritis and myopathy before coding.