ANCA-Associated Vasculitides The according to their immunoserological markers (anti-neutrophil cytoplasmic antibodies - ANCA) named ANCA-associated vasculitides (AAV) are classified following the Chapel Hill nomenclature (2012). Microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (EGPA) are categorized according to clinical, histological, and imaging findings. GPA and EGPA mainly differ from MPA in the presence of granulomatous inflammation within the airways.