Ankylosing spondylitis coexists with rheumatoid arthritis and Sjögren's syndrome: a case report with literature review.

Rheumatoid arthritis (RA), ankylosing spondylitis (AS), and Sjögren's syndrome (SS) are the most common rheumatic diseases. However, a coexistence of AS and RA or SS in the same patient is rare. What' s more, the case of AS coexists with RA, and SS is not be found yet. Here, we present a 65-year-old male patient who develop typical clinical symptoms of AS, RA, and SS successively (such as inflammatory low back pain, symmetrical small joint swelling and pain, and severe dryness of mouth and eyes) and was finally diagnosed with AS coexisting with RA and SS.