Page 51 - SPONDYLOARTHRITIS IN COLOMBIA -

INTRODUCTION
Spondyloarthritis (SpA) comprises a heterogeneous group of related diseases that are genetically linked and share characteristic clinical features associated with the inflammation of sacroiliac joints and the presence of HLA-B27 1. Clinically, SpA patients may present with axial and peripheral joint manifestations, entheseal involvement, and extra-articular features, such as uveitis and psoriasis 2. In addition to clinical findings, imaging [radiography and sacroiliac joint magnetic resonance imaging (SI-MRI)] 3 and laboratory data [HLA-B27 and C-reactive protein (CRP)] 4 are important diagnostic tools in clinical practice.
In the last two decades, MRI has been increasingly used to assess patients with clinically suspected SpA 5. Currently, MRI has become an important tool in SpA and its introduction as a diagnostic test for SpA has been a major advance 6, mainly because active inflammatory lesions are visible on MRI long before definite lesions on conventional radiographs are detectable 7. It makes MRI the most sensitive imaging modality available for the detection of sacroiliitis.
Since the role of HLA-B27 as a marker of AS has first been reported in 1973, its potential role in the diagnosis, prognosis and management of SpA has been extensively investigated. HLA-B27 is known to be associated with earlier age at disease onset in ankylosing spondylitis (AS) 8, increased severity and persistence of SI-MRI- inflammation in patients with inflammatory back pain (IBP) 9 and with a higher likelihood of a positive SI-MRI in patients with early IBP 4. Additionally, HLA-B27 has been associated with anterior uveitis in SpA patients 10.
The relevance of MRI and HLA-B27 as central parameters in defining the spectrum of SpA is obvious for many reasons: First, these parameters have been included in the classification criteria: HLA-B27
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