MPO and vasculitis: Given the presence of abnormal vasculature, a vasculitis workup was ordered, including a rheumatoid factor, antinuclear antibodies (ANA), antineutrophil cytoplasmic antibodies (c-ANCA), perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), myeloperoxidase (MPO) antibodies, anti-Jo-1 antibody, anti-Smith antibody, anti-ribonucleoprotein (anti-RNP) antibody, anti-double-stranded DNA (anti-dsDNA) antibody, anti-Ro antibody, and anti-La antibody, which all came back negative.