Vasculitis is a disorder of blood vessel inflammation, with the precise driver for this inflammation often unknown. Patients can present with acute and chronic sx, often affecting multiple organ systems. This family of problems is typically organized based on the size of the vessles infolved. In addition, a number of autoimmune disorders (e.g. SLE) may have vasculitis as a contributing feature. There are also variants which remain confined to single organ systems and/or have etiologies as described below.