Revised UIP/IPF diagnoses after the 2018 international guidelines: a 15-year Padova-Strasbourg experience

Improved knowledge has highlighted the importance of additional histological and clinico/radiological features for the diagnosis of Usual Interstitial Pneumonia(UIP)-non Idiopathic Pulmonary Fibrosis(IPF) patients. We present preliminary findings of bicentric revised UIP/IPF cases after a multidisciplinary discussion (MDD) according to the 2018 ATS/ERS/JRS/ALAT Guidelines. All 2002-2017 cases with diagnosis of IPF were retrieved. Histological review was performed considering features suggestive of other diagnoses, i.e.connective tissue diseases (CTD) (germinal centers, >4 lymphoid follicles/cm2, lymphocyte/plasma-cell ratio ≥1, lymphocytic pleuritis, vessel remodelling) and chronic hypersensitivity pneumonitis (CHP) (bridging fibrosis, peribronchial metaplasia, centrolobular fibroblastic foci, granulomas/giant-cells). Clinico/radiological data were reviewed and all cases were re-categorized after MDD. 62 cases were reviewed:in 47% the final diagnosis was IPF, in 11% IPF(likely), in 13% indeterminate IPF and in 29% non-IPF. Among the “indeterminate IPF”, the most prevalent diagnosis was CHP, while in the “non-IPF”, CHP and CTD were almost equally detected (see Figure). In conclusion, the rate of IPF diagnoses appears to have been overestimated. The current knowledge and good practice of MDD have significantly improved the diagnostic accuracy.