Review Article The current concept of spondyloarthritis with special emphasis on undifferentiated spondyloarthritis

In a recent international workshop for ankylosing spondylitis (AS), a consensus was reached that the term ‘spondyloarthritis’ is preferable to ‘spondyloarthropathy’, to emphasize the inflam-matory nature of these diseases [1]. The term is often quoted in the plural form, ‘the spondyloarthritides’, accentuating that this is a group of similar diseases with distinct clinical features and a common genetic predisposition, rather than one disease with different clinical presentations. The main association recognized is with HLA B27 but it is clear that there are other genes involved, including the interleukin-1 family gene cluster [2, 3]. Irrespective of the subtype of spondyloarthritis (SpA), the main clinical manifestations of this group are inflammatory back pain (IBP), peripheral arthritis, enthesitis and anterior uveitis, while other organ manifestations are rare. Psoriasis an