Inflammatory Diseases

In this chapter, we present four inflammatory disorders: juvenile idiopathic arthritis (JIA), Henoch-Schönlein purpura (HSP), Kawasaki disease (KD), and multisystem inflammatory syndrome in children (MIS-C). Each disorder has its own distinctive clinical presentation; however, one common thread is that each diagnosis involves immune dysregulation leading to a downstream systemic inflammatory condition. As a result, the combination of clinical manifestations is imperative in defining these disorders. JIA is a collection of inflammatory arthritides and has seven subtypes, including a systemic subtype, depending on the pattern of involvement. HSP is a systemic vasculitis that involves inflammation of the skin, gastrointestinal tract, joints, and kidneys. KD is a systemic vasculitis that involves small-to-medium arteries leading to multisystem involvement, with the most feared complication of coronary artery aneurysms. MIS-C, the newest systemic vasculitis in children, is a direct reaction to SARS-CoV-2; while it can closely resemble KD, it does hold distinctive systemic involvement that distinguishes it from KD. Overall, these inflammatory disorders require a comprehensive history with particular attention to clinical manifestations to help clinicians differentiate them, determine further workup, and solidify the diagnosis.