MPO and rheumatoid arthritis: Patients were diagnosed with SSc (n = 7), IIM (n = 6), ASS (n = 6), amyopathic DM (n = 1), RA (n = 5), interstitial pneumonia with autoimmune features (IPAF) (n = 3), pSS (n = 3), and myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) positive (n = 2).