A 2020 international consensus on testing ANCAs beyond systemic vasculitis suggested that MPO-ANCA and PR3-ANCA should be tested in all patients with Idiopathic Interstitial Pneumonia (IIP) and included in the serologic criteria for IPAF or UIPAF, a condition of IPAF with a Usual Interstitial Pneumonia (UIP) radiological pattern even though this feature is not included among the morphological domain proposed in these criteria [19,20]. Here, PRTN3 is linked to idiopathic interstitial pneumonia.