What is your approach in differentiating IPAF (interstitial pneumonia with autoimmune features) versus "CTD ILD" in patients with serologic abnormalities but do not fulfill criteria for autoimmune disease?

Even for those of us who work in ILD clinics, this can be a challenging issue. The concept of IPAF (interstitial pneumonia with autoimmune features) was developed in 2015 jointly by the ATS and the ERS for study purposes and as such is somewhat helpful in the clinic. Much like classification criteri...