Updated European Respiratory Society-American Thoracic Society (ERS-ATS) Classification of Interstitial Pneumonias: The Radiologic Perspective.

This review aims to summarize the key features of the 2025 update of the European Respiratory Society-American Thoracic Society Classification of Interstitial Pneumonias from a radiologic perspective. It highlights the revised terminology, pattern definitions, and conceptual framework, which moves beyond the previous focus on idiopathic interstitial pneumonias toward a broader radiologic-pathologic pattern-based approach that includes both idiopathic and secondary causes. Three major interstitial patterns are defined: usual interstitial pneumonia, nonspecific interstitial pneumonia, and bronchiolocentric interstitial pneumonia. The last is introduced as a unifying descriptor for airway-centered diseases, including hypersensitivity pneumonitis and akin conditions. Within the alveolar filling disorders, the term desquamative interstitial pneumonia is replaced by the more pathologically consistent term alveolar macrophage pneumonia. A further key update is the formal incorporation of diagnostic confidence levels, encouraging the explicit reporting of uncertainty to better guide additional investigations and therapeutic decisions.