Enthesitis related arthritis- 2 distinct clinical phenotypes?

Background Enthesitis related arthritis (ERA) is the subtype of juvenile idiopathic arthritis (JIA) as defined by the International League of Associations for Rheumatology (ILAR) classification (2004). Asymmetrical lower limb arthritis and enthesitis are said to be prominent early features with axial inflammation a late feature. In our cohort of patients with ERA we observed this was often not the casewith axial inflammation occurring early and the emergence of 2 distinct clinical phenotypes.