Diagnostic Unification of Usual Interstitial Pneumonia is a Step Back

We read with interest the Personal View published by Selman and colleagues.1Selman M Pardo A Wells AU Usual interstitial pneumonia as a stand-alone diagnostic entity: the case for a paradigm shift?.Lancet Respir Med. 2023; 11: 188-196Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar These authors propose that the usual interstitial pneumonia (UIP) pattern be considered a single and discrete entity, consolidating primary and secondary causes. The authors note that shared pathogenic mechanisms and similarities in disease behaviour support this unification and suggest this approach would facilitate earlier anti-fibrotic therapy and clinical trials. However, we urge caution with this approach. Although UIP has been shown in multiple studies to be associated with a poor prognosis when compared with other pathological patterns, these findings relate to populations, not individual patients. In our institutional experience, we see substantial clinical variability in the course of UIP, whether from idiopathic pulmonary fibrosis or other causes. Thus, we worry that lumping patients with UIP together will lead to further misperceptions about treatment options and prognosis in a field already filled with confusion. Moreover, lumping patients with UIP in a category similar to idiopathic pulmonary fibrosis connotes that immunosuppression is inappropriate and that patients with autoimmune interstitial lung disease or chronic hypersensitivity pneumonitis should not be treated with these agents. Although this might be true, we and others2Fischer A Brown KK Du Bois RM et al.Mycophenolate mofetil improves lung function in connective tissue disease-associated interstitial lung disease.J Rheumatol. 2013; 40: 640-646Crossref PubMed Scopus (286) Google Scholar believe that immunosuppression should be the first line therapy for all patients with autoimmune lung disease, regardless of pathology or imaging findings. Furthermore, testing to confirm UIP in patients with autoimmune disease could incur unnecessary risk without clear benefits in terms of management. Finally, the lumping approach ignores data showing that some patients have both UIP and non-UIP features in their histopathology and argues against the importance of a multidisciplinary team approach to arriving at accurate diagnoses.3Flaherty KR Travis WD Colby TV et al.Histopathologic variability in usual and nonspecific interstitial pneumonias.Am J Respir Crit Care Med. 2001; 164: 1722-1727Crossref PubMed Scopus (588) Google Scholar In conclusion, we suggest that the diagnostic unification of UIP has disadvantages despite the very thoughtful and persuasive arguments laid out by Selman and colleagues. GG has received consulting fees from United Therapeutics and honoraria from the Milken Institute. RS has received grant support from the US National Institutes of Health and has received consulting fees from Iliad Biotechnologies. DK declares no competing interests. Usual interstitial pneumonia as a stand-alone diagnostic entity: the case for a paradigm shift?Usual interstitial pneumonia (UIP) is characterised by a distinctive morphological and radiological appearance that was considered the pathognomonic hallmark of idiopathic pulmonary fibrosis (IPF). However, this peculiar lung remodelling pattern is also seen in other fibrotic interstitial lung diseases, including hypersensitivity pneumonitis, and connective tissue diseases. In this Personal View, we advocate the designation of a UIP pattern as a single, discrete diagnostic entity, amalgamating its primary form and secondary processes in disorders such as hypersensitivity pneumonitis (hypersensitivity pneumonitis with UIP), rheumatoid arthritis (rheumatoid arthritis with UIP), and others. Full-Text PDF Diagnostic unification of usual interstitial pneumonia is a step back – Authors' replyWe read with interest the comments by Gautam and colleagues related to our Personal View, in which we proposed that the usual interstitial pneumonia (UIP) pattern found in idiopathic pulmonary fibrosis and several other interstitial lung disease subtypes transcends the diagnostic labels currently assigned to them since it exhibits striking similarities in disease behaviour and pathogenic profile and invariably affects the clinical course and prognosis.1 However, we do not argue that identical outcomes will be seen in individual patients with UIP and nor do we advocate uniform UIP management. Full-Text PDF