Demystifying idiopathic interstitial pneumonia: time for more etiology-focused nomenclature in interstitial lung disease

ABSTRACT

Introduction

A major focus of interstitial lung disease (ILD) has centered on disorders termed idiopathic interstitial pneumonias (IIPs) which include, among others, idiopathic pulmonary fibrosis, idiopathic nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, and respiratory bronchiolitis-interstitial lung disease.

Areas Covered

We review the radiologic and histologic patterns for the nine disorders classified by multidisciplinary approach as IIP, and describe the remarkable amount of published epidemiologic, translational, and molecular studies demonstrating their associations with numerous yet definitive environmental exposures, occupational exposures, pulmonary diseases, systemic diseases, medication toxicities, and genetic variants.

Expert Opinion

In the 21st century, these disorders termed IIPs are rarely idiopathic, but rather are well-described radiologic and histologic patterns of lung injury that are associated with a wide array of diverse etiologies. Accordingly, the idiopathic nomenclature is misleading and confusing, and may also promote a lack of inquisitiveness, suggesting the end rather than the beginning of a thorough diagnostic process to identify ILD etiology and initiate patient-centered management. A shift toward more etiology-focused nomenclature will be beneficial to all, including patients hoping for better life quality and disease outcome, general medicine and pulmonary physicians furthering their ILD knowledge, and expert ILD clinicians and researchers who are advancing the ILD field.

KEYWORDS:

• Idiopathic interstitial pneumonia
• interstitial lung disease
• idiopathic pulmonary fibrosis
• usual interstitial pneumonia
• nonspecific interstitial pneumonia
• organizing pneumonia

Article highlights

• A major focus of interstitial lung disease (ILD) centers on nine disorders termed idiopathic interstitial pneumonias (IIPs), which include idiopathic pulmonary fibrosis

• Since their original descriptions, substantial epidemiologic, translational, and molecular studies have demonstrated that IIPs are driven by combinations of environmental and occupational exposures, autoimmune mechanisms, pulmonary and systemic diseases, medication toxicities, and genetic variants

• The IIPs are thus rarely idiopathic in the 21st century, and the idiopathic nomenclature is often misleading and confusing

• Rather than being idiopathic, the IIPs are well-described radiologic and histologic patterns of lung injury that are associated with a wide array of diverse etiologies

• A shift towards more etiology-focused nomenclature will provide better clarity and understanding in ILD, and will be beneficial to all, including patients, general medicine and pulmonary physicians, and expert ILD clinicians and researchers

Declaration of interest

NWT, SPA, IGL, NGS, AJG and JRG have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript, including employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. SEH is supported by a United States Building Trades Medical Screening Program to support surveillance and screening related to occupational lung disease. EJB receives miscellaneous honorariums from Boehringer Ingelheim, Inc for speaking engagements, and has served as the study site PI at the University of Maryland School of Medicine for pulmonary fibrosis clinicals trials with Galapagos, Inc. and Galecto, Inc

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This work was supported by the United States National Institutes of Health NIH-NIAMS R01AR077562 and NIH-NHLBI R01HL126897, and United States Veterans Affairs Merit Award I01BX002499.