Multidisciplinary Approach to Diffuse Lung Diseases (2025)-W6-CCH09-2025

Video Transcription

Video Summary

The session explains how multidisciplinary discussion (MDD) integrates clinical history, high-resolution CT (HRCT), and lung pathology to reach the most confident diagnosis in fibrotic interstitial lung disease (ILD). The speakers focus on three common fibrotic patterns: usual interstitial pneumonia (UIP), fibrotic nonspecific interstitial pneumonia (NSIP), and fibrotic hypersensitivity pneumonitis (HP). They emphasize that UIP and NSIP are <em>patterns</em>, not final diagnoses, and that classification issues continue—especially around “bronchiolocentric interstitial pneumonia” (BIP), sometimes used for antigen-negative chronic HP.

Radiology highlights key fibrosis markers (reticulation, traction bronchiectasis, architectural distortion, and honeycombing). Definite UIP requires honeycombing; probable UIP has the same basal subpleural fibrosis pattern without honeycombing. Fibrotic NSIP tends to be lower-lobe predominant with ground-glass change, possible subpleural sparing, and no honeycombing. Fibrotic HP is more variable in distribution and is suggested by mosaic attenuation, air trapping, centrilobular nodules, and the “three-density sign.”

Pathology contrasts UIP’s patchy, temporally heterogeneous fibrosis with fibroblastic foci and honeycomb change versus NSIP’s temporally homogeneous, diffuse alveolar wall fibrosis with preserved architecture. Fibrotic HP often shows bronchiolocentric fibrosis, peribronchiolar metaplasia, and sometimes granulomas, though granulomas may be absent in advanced disease.

Three cases demonstrate MDD: (1) probable UIP on HRCT with UIP histology and no exposures/autoimmunity → idiopathic pulmonary fibrosis (IPF), noting biopsy is often unnecessary in probable UIP; (2) classic NSIP imaging and fibrotic NSIP pathology with minimal autoimmune features → idiopathic NSIP with monitoring for later connective tissue disease; (3) bird exposure plus three-density sign and bronchiolocentric/UIP-like fibrosis → fibrotic HP.

Keywords

multidisciplinary discussion (MDD)

fibrotic interstitial lung disease (ILD)

high-resolution CT (HRCT)

usual interstitial pneumonia (UIP)

fibrotic nonspecific interstitial pneumonia (NSIP)

fibrotic hypersensitivity pneumonitis (HP)

three-density sign

honeycombing

bronchiolocentric interstitial pneumonia (BIP)

idiopathic pulmonary fibrosis (IPF)