Interstitial lung diseases

Over 200 interstitial lung diseases, from ultra rare to relatively common, are recognised. Most interstitial lung diseases are characterised by inflammation or fibrosis within the interstitial space, the primary consequence of which is impaired gas exchange, resulting in breathlessness, diminished exercise tolerance, and decreased quality of life. Outcomes vary considerably for each of the different interstitial lung diseases. In some conditions, spontaneous reversibility or stabilisation can occur, but unfortunately in many people with interstitial lung disease, especially in those manifesting progressive pulmonary fibrosis, respiratory failure and death are a sad reality. Over the past 3 years, the field of interstitial lung disease has had important advances, with the approval of drugs to treat systemic sclerosis-associated interstitial lung disease, interstitial lung disease-associated pulmonary hypertension, and different forms of progressive pulmonary fibrosis. This Seminar provides an update on epidemiology, pathogenesis, presentation, diagnosis, disease course, and management of the interstitial lung diseases that are most frequently encountered in clinical practice. Furthermore, we describe how developments have led to a shift in the classification and treatment of interstitial lung diseases that exhibit progressive pulmonary fibrosis and summarise the latest practice-changing guidelines. We conclude with an outline of controversies, uncertainties, and future directions.

Automated summary

There are over 200 recognized interstitial lung diseases, which vary in rarity. Most of these diseases are characterized by inflammation or fibrosis in the interstitial space, leading to impaired gas exchange and resulting in symptoms such as breathlessness, decreased exercise tolerance, and reduced quality of life. The prognosis for different interstitial lung diseases varies considerably, with some conditions showing reversibility or stabilization, while others lead to respiratory failure and death. Recent advances in the field have led to the approval of drugs for the treatment of specific interstitial lung diseases, including systemic sclerosis-associated interstitial lung disease, interstitial lung disease-associated pulmonary hypertension, and progressive pulmonary fibrosis.