An Update on Diagnosis and Classification of Axial Spondyloarthritis.

To summarize the most relevant recent progress to diagnose and classify patients with axial spondyloarthritis (axSpA). A substantial proportion of new studies focused on the diagnosis and classification of patients with axSpA. Efforts have been concentrated on setting the best strategy to refer patients with suspected axSpA and evaluating the utility of different tools during the diagnostic work-up, especially of imaging techniques. On top of this, researchers have worked on addressing some concerns raised about the employment of the Assessment of SpondyloArthritis international Society classification criteria, especially those related to the validity and misuse of the criteria, providing valuable data on this regard. Recent findings emphasize that classification should serve a completely different purpose than diagnosis. In addition, they highlight the importance to consider the limitations for imaging acquisition, the appropriate context, and differential diagnosis when interpreting imaging findings during the diagnostic work-up of patients with suspected axSpA.