Usefulness of ultrasonography-proven tenosynovitis to monitor disease activity of a patient with very early rheumatoid arthritis treated by abatacept.

We introduced abatacept (ABT) in a very early rheumatoid arthritis (RA) patient with active tenosynovitis of hands defined by musculoskeletal ultrasonography (MSKUS). MSKUS-proven tenosynovitis remarkably improved at 2 months in spite of clinical exacerbation, followed by clinical remission at 5 months. MSKUS abnormalities also disappeared. Although ABT was discontinued due to an adverse event after the sixth infusion, she remained in clinical remission as well as imaging remission by MSKUS at 13 months.