MPO and vasculitis: Rheumatologic disease, such as CNS lupus or vasculitis, was excluded, because the serological tests for antinuclear antibody, Rh factor, antimitochondrial antibody, proteinase-3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) and myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) were negative.