MPO and interstitial lung disease: Also, in ANCA-ILD, diagnosis can be challenging, because ILD can precede the typical manifestations of vasculitides by years in 14–85% of patients; the prevalence of ANCA in patients initially presented with IPF ranges between 4 and 36% for MPO-ANCA and 2–4% for PR3-ANCA; and even in histological lung samples, despite the possible presence of NSIP features as a minor associated pattern, signs of vasculitis and capillaritis are rare [35].