ANCA-associated vasculitis (AAV) are a systemic autoimmune disease that primarily affect small vessels, according to the Chapel Hill classification [1] and cause necrotizing vasculitis and result from the production of autoantibodies targeting the cytoplasm of neutrophils (ANCA). They include eosinophilic granulomatosis with polyangiitis (EGPA), granulomatosis with polyangiitis (GPA), and microscopic polyangiitis (MPA) [2].
