Usual interstitial pneumonia end-stage features from explants with radiologic and pathological correlations

Area of Science:

• Pulmonary Medicine
• Pathology
• Radiology

Background:

• Idiopathic pulmonary fibrosis (IPF) is a severe interstitial pneumonia with characteristic HRCT and UIP patterns.
• Differential diagnosis includes fibrotic nonspecific interstitial pneumonia (F-NSIP).
• Histological features of UIP are well-described in biopsies, but less is known from explants.

Purpose of the Study:

• To histologically analyze UIP/IPF explants.
• To compare explant findings with open lung biopsies (OLBs) and HRCT.
• To identify characteristic and confounding lesions in UIP/IPF explants.

Main Methods:

• Histological analysis of 22 UIP/IPF explants.
• Comparison with 11 UIP/IPF OLBs and 19 HRCT scans.
• Assessment of temporospatial heterogeneity, fibrosis patterns, fibroblastic foci, honeycombing, and other lesions.

Main Results:

• UIP/IPF explants and OLBs showed similar temporospatial heterogeneity and subpleural/paraseptal fibrosis.
• Explants had significantly higher scores for fibroblastic foci and honeycombing compared to OLBs.
• Explants frequently exhibited NSIP areas (60%), peribronchiolar fibrosis (41%), and large airspace enlargements with fibrosis (59%).
• HRCT showed honeycombing (95%) and ground-glass opacities (53%), correlating with NSIP areas or acute exacerbation.
• Combined IPF and emphysema occurred in 6 patients; lesions were more severe in explants.

Conclusions:

• UIP/IPF explants display more severe disease and a higher prevalence of confounding lesions than biopsies.
• Findings suggest disease worsening and potential diagnostic overlap with NSIP in advanced IPF.
• HRCT findings correlate with histological features, aiding in diagnosis and management.