Rheumatoid arthritis w/o rheumatoid factor, right ank/ft

This diagnosis code signifies chronic inflammatory arthritis affecting the joints of the right ankle and/or foot, specifically when laboratory tests for rheumatoid factor (RF) are negative. This form of rheumatoid arthritis is seronegative, meaning the characteristic autoantibody is not detected in the patient's blood.

Apply this code when documentation confirms a diagnosis of seronegative rheumatoid arthritis with involvement localized to the right ankle and/or foot. Supporting documentation should include physician's diagnosis, imaging findings consistent with inflammatory arthritis, and negative rheumatoid factor test results.

• Ensure laterality (right) and specific joint involvement (ankle and foot) are clearly documented.
• Distinguish from seropositive rheumatoid arthritis (M05.-) and other inflammatory arthropathies.
• Confirm negative rheumatoid factor results are present in the patient's medical record.