ABSTRACT
The systemic vasculitides are a group of diverse diseases characterized by blood vessel inflammation. The existing classification criteria are intended to create homogeneous patient groups for research and not to diagnose individual patients. However, they have been misused as diagnostic criteria, in both practice and research. The existing classification systems for vasculitis are limited by the overlapping features of disease entities and unrecognized pathogenic mechanisms. This review discusses the benefits and limitations of the widely used American College of Rheumatology criteria and Chapel Hill Consensus Conference nomenclature, updated in 2012. Improved diagnostics, including antineutrophil cytoplasmic antibody (ANCA) testing and imaging, argue for updating the established classification criteria. International efforts are underway to build a more effective classification and diagnostic criteria that reflect a better understanding of the pathophysiology of vasculitis and recent discoveries of genetics and biomarkers.