MPO and microscopic polyangiitis: PR3-ANCA account for the majority of ANCA with cytoplasmic immunofluorescence patterns (C-ANCA) and are commonly associated with GPA (60-80% of the cases), whereas MPO-ANCA usually match ANCA with perinuclear immunofluorescence pattern (P-ANCA) and are more common in patients with MPA (80-90% of the cases) or EGPA (35-40% of the cases) [2].