MPO and anti-neutrophil cytoplasmic antibody-associated vasculitis: Two out of five patients were positive for anti-neutrophil cytoplasmic antibodies (ANCAs) without clinical or laboratory evidence of ANCA-associated vasculitis (AAV), as confirmed by ELISA: anti-proteinase 3 antibodies at 7.3 IU/mL (reference <2.0 IU/mL) in patient No. 3, and anti-myeloperoxidase antibodies at 5.3 IU/mL (reference <2.0 IU/mL) in patient No. 1.