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Clinical aspects of juvenile and adult ankylosing spondylitis.

Ankylosing spondylitis (AS) is a heterogeneous and systemic rheumatic disorder that is characterized primarily by inflammation of the spine and sacroiliac joints. Consequently, back pain is a frequent presenting complaint although the disease can begin with peripheral arthritis as well as acute anterior uveitis. Unlike men, however, women appear to have milder or atypical AS that may go unrecognized for years. Moreover, the presentation in children rests on the recognition of two distinct subgroups that may be indistinguishable from juvenile chronic polyarthritis. The more frequent subgroup includes primarily teenage boys who present initially with an asymmetric peripheral pauciarthritis that most often affects lower-limb joints. Only some years later does sacroiliitis evolve, and, much later still, back complaints or other clinical and radiographic features typical of AS. A second subgroup includes mostly girls with a polyarticular onset that is subsequently characterized by cervical fusion, micrognathia, acute anterior uveitis, sacroiliitis, spondylitis, and rheumatoid-like hands that persist into adulthood.