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Review
. 2022 Jan;35(Suppl 1):8-14.
doi: 10.1038/s41379-021-00889-5. Epub 2021 Aug 31.

The histologic diagnosis of usual interstitial pneumonia of idiopathic pulmonary fibrosis. Where we are and where we need to go

Maxwell L Smith  1
Affiliations
Review

The histologic diagnosis of usual interstitial pneumonia of idiopathic pulmonary fibrosis. Where we are and where we need to go

Maxwell L Smith. Mod Pathol. 2022 Jan.

Abstract

In the 50 years since its inception by Dr. Liebow, the diagnosis of usual interstitial pneumonia (UIP) by pathologists has changed significantly. This manuscript reviews the progressive history of the histologic diagnosis of UIP and summarizes the current state of histologic UIP and its relationship to the clinical syndrome idiopathic pulmonary fibrosis (IPF). Fibrotic lung disease mimics of UIP/IPF are reviewed and pearls for distinguishing these diseases from UIP/IPF are provided. Strategies for increasing the value of histologic assessment of biopsies in the setting of pulmonary fibrosis are also discussed.

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Conflict of interest statement

The author declares no competing interests.

Figures

Fig. 1
Fig. 1. Usual interstitial pneumonia.
Scanning magnification shows areas of advanced fibrosis with architectural distortion (A). Fibrosis at the periphery of the lobule (arrows) with sparring of the centrilobular regions (B). Sharp demarcation between the advanced fibrosis and the normal appearing alveolar walls (C). Evidence of active injury in the form of fibroblast foci (asterisks) (D).
Fig. 2
Fig. 2. Honeycomb lung.
Dilated cystic spaces embedded within advanced fibrosis (A). The cysts are lined by ciliated respiratory epithelium and the spaces are often filled with mucous debris (B).
Fig. 3
Fig. 3. Fibrotic hypersensitivity pneumonitis.
Patchy advanced pulmonary fibrosis (A) with areas of honeycomb (B) reminiscent of UIP/IPF. Peribronchiolar metaplasia that is out of proportion to the degree of scarring in the lobule (C). Poorly formed interstitial granuloma confirming the diagnosis of hypersensitivity pneumonitis (D).
Fig. 4
Fig. 4. Connective tissue disease-associated fibrosing interstitial lung disease.
Patchy advanced pulmonary fibrosis with areas of possible sparing from low power (A) and fibroblast foci (asterisks) (B) reminiscent of UIP/IPF. Lymphoplasmacytic infiltrates in the “normal” alveolar walls (C). Numerous lymphoid follicles including some with germinal centers (arrows) (D).
Fig. 5
Fig. 5. Fibrotic nonspecific interstitial pneumonia.
Pulmonary fibrosis with apparent geographic heterogeneity from low power (A) and fibroblast foci (arrow) (B) reminiscent of UIP/IPF. Subtle nonspecific interstitial pneumonia infiltrates in the less fibrotic areas (C). Lymphoplasmacytic interstitial infiltrates (D).
See this image and copyright information in PMC

References

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