ⒸPathologynuggets. Notes to review for medical students, residents, and doctors. Vasculitides are autoimmuine disorders characterized by inflammation of blood vessels. Most of them are chronic systemic disorders that affect the multiple systems and should be considered in differential diagnoses of any multisystem illness. Vasculitis can be divided into large vessel, medium vessel or small vessel vasculitis based on the size of the vessels involved. Large Vessel Vasculitis ‌Giant cell arterities or Temporal arteritis Takayasu arterities Medium Vessel Vasculitis ‌Polyarterities Nodosa Kawasaki Disease Small Vessel Vasculitis ‌Granulomatosis with Polyangitis(GPA) ‌Microscopic polyangitis (MPA) ‌Eosinophilic Granulomatosis with Polyangitis (EGPA)               **  Small vessel vasculitides GPA, MPA and EGPA are also known as ANCA                                              associated vasculitides (AAVs). ** Immune complex small vessel vasculitides ‌      IgA vasculi