Spondyloarthritis and enthesopathy. Current concepts in rheumatology.

Spondyloarthritis (Sp) is newly defined as arthritis that is clinically, pathologically, and genetically related to and predisposed to ankylosing spondylitis (AS) and Reiter's syndrome (RS) rather than to rheumatoid arthritis (RA). A diagnosis of Sp does not necessarily imply arthritis of the spine and does not depend on the demonstration of roentgenographic sacroiliitis that, in this conceptualization, is recognized not as the essential hallmark, but rather merely as a diagnostic "way station" on a continuum of disease, which may (but need not necessarily) begin with RS or be complicated during its course by AS or RS. Spondyloarthritis is distinctively characterized morphologically and clinically by disproportionate inflammation at the entheses, the sites of attachment of tendons and ligaments to bone. Family history or presence of enthesopathic pain, psoriasis, inflammatory bowel disease, uveitis, recurrent urethritis, prostatitis or cervicitis, keratoderma blennorrhagicum, HLA-B27, and asymmetric pauciarticular lower lower extremity arthritis without rheumatoid factor or rheumatoid nodules suggests a diagnosis of Sp rather than RA.