特発性間質性肺炎

OBJECTIVES: Histopathological usual interstitial pneumonia (UIP) features are associated with progressive fibrosis but may be overlooked in smokers, where emphysema and smoking-related fibrosis complicate CT-based UIP classification. This study aimed to develop and validate a CT-based score to detect histopathological UIP features and to evaluate its association with disease progression in smokers with fibrotic idiopathic interstitial pneumonia (IIP). MATERIALS AND METHODS: This retrospective multicentre study included two biopsy-proven cohorts of smokers with fibrotic IIP: derivation (n = 242; nationwide registry) and validation (n = 126; single-centre database, 2008-2013). Three predefined HRCT findings-upper-lobe irregular lines (U), irregularity of pleural surface (I), and pleural-based basal reticulation (P)-were scored (0/1) and summed as the U-I-P score (0-3). Associations with histopathological UIP features and outcomes were assessed using logistic regression, receiver operating characteristic analysis, Cox proportional hazards models, and bootstrap internal validation. RESULTS: Cohorts were similar (median age 65 vs. 64 years; 88% vs. 87% male). Histopathological UIP features were present in 208/242 (86%) and 109/126 (87%) patients. The U-I-P score independently predicted histopathological UIP features in both cohorts (area under the curve, 0.83 and 0.89; both p < 0.001). Bootstrap validation demonstrated minimal optimism, supporting model stability. The U-I-P score independently predicted disease progression at 1 and 2 years in the validation cohort (p = 0.002 and p = 0.001, respectively). CONCLUSION: The U-I-P score detects histopathological UIP features and predicts disease progression in smokers with fibrotic IIP, providing a practical imaging biomarker, even in cases with atypical CT patterns. KEY POINTS: Question: In smokers with fibrotic interstitial lung disease, emphysema and smoking-related fibrosis complicate CT pattern classification, limiting identification of usual interstitial pneumonia pathology. FINDINGS: The U-I-P (upper-lobe irregular lines, irregularity of pleural surface, pleural-based reticulation) score detected histopathological usual interstitial pneumonia features and predicted progression. CLINICAL RELEVANCE: The U-I-P score aids identification of smokers with usual interstitial pneumonia-type fibrosis and increased risk of progression when biopsy is unavailable, or CT patterns are atypical for usual interstitial pneumonia.

The update of the American Thoracic Society/European Respiratory Society (ATS/ERS) classification of interstitial pneumonias published in 2025 extends the oprior classification system beyond merely idiopathic entities, now also encompassing entities with identifiable triggers [1]. The core component of this update is the terminological reorientation of the classification towards a descriptive, primarily morphologically oriented concept with the aim of a clear differentiation of radiological and histological patterns from clinically defined diseases. Acute interstitial pneumonia (AIP) is now designated as idiopathic diffuse alveolar damage (DAD), and desquamative interstitial pneumonia (DIP) as alveolar macrophage pneumonia (AMP). The pattern of bronchiolocentric interstitial pneumonia (BIP) has been introduced as an independent morphological pattern, reserving the term hypersensitivity pneumonitis (HP) exclusively for multidisciplinary diagnosis in the future. Furthermore, the updated classification provides a biologically founded and clinically applicable categorization system of interstitial and alveolar filling patterns and the prognostically relevant separation into fibrotic and nonfibrotic phenotypes. Also, there is a stronger emphasis on the transparent reporting of the diagnostic confidence by interstitial lung disease (ILD) boards, including the use of "provisional" diagnoses or of the term "unclassifiable ILD" in cases of low and very low diagnostic certainty. The current classification can help to standardize the diagnostic course and to make the decision-making process in the ILD board more transparent. It is to be expected that this update will be the foundation for future research and for new knowledge in the field of ILD. In addition, it should however not be ignored that the new classification has been critisized by some experts with respect to the introduction of the pattern of BIP and the provisional entity of "idiopathic BIP". It is feared that this change in terminology emphasizing the morphological pattern rather than causative factors could lead to reduced attention concerning potential trigger exposures in the diagnostic process.

BACKGROUND: Interstitial lung diseases (ILDs) are a heterogeneous group of pulmonary disorders that can result in acute or chronic forms of respiratory failure. Prior studies have shown high mortality among patients with ILD receiving intensive care, but most have focused on idiopathic pulmonary fibrosis (IPF) and have not characterized other ILD subgroups. RESEARCH QUESTION: Does 90-day transplant-free survival differ by ILD subgroup in patients with acute respiratory failure (ARF) requiring respiratory support? STUDY DESIGN AND METHODS: We conducted a retrospective cohort study of adults with ILD admitted to 5 hospitals within our health system (2017-2024) using electronic record health data. We pragmatically defined ARF as receipt of ≥ 24 continuous hours of invasive or noninvasive respiratory support. We identified ILD diagnosis using validated International Classification of Diseases, version 10, Clinical Modification codes categorized into IPF/idiopathic interstitial pneumonia, connective tissue disease-associated ILD (CTD-ILD), exposure-related ILD, sarcoidosis, or other ILD. We evaluated 90-day transplant-free survival with multivariable Cox proportional hazards models adjusted for demographics, comorbidities, hospital type, and acute illness severity. Secondary outcomes included in-hospital death or hospice discharge and hospital length of stay. RESULTS: Among 982 patients with ILD and ARF (median age, 70 years; 50% female), 269 (27%) were categorized as IPF/idiopathic interstitial pneumonia, 74 (8%) were categorized as CTD-ILD, 57 (6%) were categorized as exposure-related ILD, 171 (17%) were categorized as sarcoidosis, and 411 (42%) were categorized as other. By day 90, 466 patients (48%) had died or underwent transplant, with rates ranging from 42% in patients with CTD-ILD to 54% in exposure-related ILD. There were no significant differences in adjusted transplant-free survival or secondary outcomes overall, or when stratified by type of respiratory support. INTERPRETATION: In this multihospital cohort of critically ill patients with ILD and ARF, 90-day transplant-free survival was poor and did not differ by ILD subgroup, even after adjustment for key confounders. These findings underscore the seriousness of ARF among patients with ILD.

Acute exacerbations (AEs) occur both in patients with idiopathic pulmonary fibrosis (IPF) and non-IPF fibrotic interstitial lung disease (fILD). These events confer high morbidity and mortality, with a lack of proven effective therapeutic interventions. The objective of this state-of-the-art document is to summarize latest evidence since the 2016 international working group report on AE-IPF, expanding it across the spectrum of all fILDs. A comprehensive literature review on the epidemiology, associated and risk factors, prognosis, and management of AE-fILD is summarized. In addition to revising the AE definition and diagnostic criteria for broad application across different fILDs, a conceptual framework for acute respiratory worsening (ARW) has been proposed to encompass a variety of acute respiratory deteriorations, both related and unrelated to AE. This allows structured evaluation in both clinical and research settings. The proposed revised definition for AE-fILD is an acute respiratory event characterized by increased respiratory symptoms or signs and associated with radiologic or histologic features consistent with diffuse alveolar damage (with or without superimposed organizing pneumonia) in a patient with known or newly diagnosed fILD. On the other hand, ARW refers to a heterogeneous group of clinical events with acute symptom worsening not attributable to DAD in patients with fILD, such as pulmonary edema, bronchitis, and pneumonia, although severe pneumonia can trigger AE-fILD. Additionally, we discuss considerations for inclusion of AE as a clinical trial endpoint, as well as research priorities for advancing knowledge on the pathogenic mechanisms, event prediction, risk stratification, and development of drugs and supportive treatments.

BACKGROUND: The radiological usual interstitial pneumonia (UIP) pattern demonstrates heterogeneity across different underlying etiologies. This study aimed to characterize its clinical and prognostic impact in primary Sjögren's syndrome-associated interstitial lung disease (pSS-ILD) and compare these features with those in idiopathic pulmonary fibrosis (IPF). METHODS: Consecutive patients with pSS-ILD and IPF were enrolled. Clinical characteristics were compared between pSS-ILD patients with (UIP-pSS) and without (non-UIP-pSS) radiological UIP, as well as between UIP-pSS and IPF patients. Risk factors for UIP pattern were identified by logistic regression. Survival was compared using log-rank test. RESULTS: In total, 558 pSS-ILD patients and 199 IPF patients were included. Radiological UIP pattern was identified in 18.8% of the pSS-ILD cohort. Compared to non-UIP-pSS patients, UIP-pSS patients were older, comprised more male patients and smokers (all p<0.05), and showed a greater prevalence of pulmonary hypertension (37.1% vs 20.5%, p=0.003). They also exhibited lower lung diffusing capacity for carbon monoxide (DLco) % predicted (p=0.043), increased composite physiologic index (CPI; p=0.016), and higher Gender-Age-Physiology (GAP) index (p=0.002). Also, UIP-pSS patients had increased 1-year (16.2% vs 6.8%, p=0.002), 3-year (34.4% vs 17.7%, p=0.001), and 5-year mortality (55.7% vs 35.0%, p=0.002). When compared to IPF controls, UIP-pSS patients demonstrated higher DLco % predicted (p<0.001), lower CPI (p=0.009) and GAP index (p<0.001), and longer median survival (66.0 vs 40.0 months, p<0.001). CONCLUSIONS: The radiological UIP pattern correlated with impaired pulmonary function and increased mortality in pSS-ILD. However, compared to IPF patients, individuals with UIP-pSS exhibited better pulmonary function and prognosis.