Reliability of histopathologic diagnosis of fibrotic interstitial lung disease:\xa0an international collaborative standardization project

Robert Camp,Irene Sansano,Anja C Roden,Richard Attanoos,Andre L Moreira,Carol Farver,Raghavendra Pillappa,Brandon T Larsen,Maxwell L Smith,Alexandre Todorovic Fabro,Robert J Homer

doi:10.1186/s12890-021-01522-6

Abstract

BackgroundCurrent interstitial lung disease (ILD) diagnostic guidelines assess criteria across clinical, radiologic and pathologic domains. Significant interobserver variation in histopathologic evaluation has previously been shown but the specific source of these discrepancies is poorly documented. We sought to document specific areas of difficulty and develop improved criteria that would reduce overall interobserver variation.MethodsUsing an internet-based approach, we reviewed selected images of specific diagnostic features of ILD histopathology and whole slide images of fibrotic ILD. After an initial round of review, we confirmed the presence of interobserver variation among our group. We then developed refined criteria and reviewed a second set of cases.ResultsThe initial round reproduced the existing literature on interobserver variation in diagnosis of ILD. Cases which were pre-selected as inconsistent with usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) were confirmed as such by multi-observer review. Cases which were thought to be in the spectrum of chronic fibrotic ILD for which UIP/IPF were in the differential showed marked variation in nearly all aspects of ILD evaluation including extent of inflammation and extent and pattern of fibrosis. A proposed set of more explicit criteria had only modest effects on this outcome. While we were only modestly successful in reducing interobserver variation, we did identify specific reasons that current histopathologic criteria of fibrotic ILD are not well defined in practice.ConclusionsAny additional classification scheme must address interobserver variation in histopathologic diagnosis of fibrotic ILD order to remain clinically relevant. Improvements to tissue-based diagnostics may require substantial resources such as larger datasets or novel technologies to improve reproducibility. Benchmarks should be established for expected outcomes among clinically defined subgroups as a quality metric.

Highlights

Current interstitial lung disease (ILD) diagnostic guidelines assess criteria across clinical, radiologic and pathologic domains
Other ILDs such as collagen vascular disease associated ILD and fibrotic hypersensitivity pneumonitis (HP) are still potentially treated with immunosuppression even though so called progressive fibrotic ILD of any association may benefit from anti-fibrotics [5]
Materials and methods A website was created for this project which displayed both fixed images of selected features relevant to diagnosis of Idiopathic pulmonary fibrosis (IPF) and whole slide images (WSI) of cases of ILD [13]

Summary

Introduction

Current interstitial lung disease (ILD) diagnostic guidelines assess criteria across clinical, radiologic and pathologic domains. Significant interobserver variation in histopathologic evaluation has previously been shown but the specific source of these discrepancies is poorly documented. We sought to document specific areas of difficulty and develop improved criteria that would reduce overall interobserver variation. Interstitial lung disease (ILD) refers to a range of diagnostic entities which show varying degrees of inflammation and fibrosis [1]. IPF was initially considered a chronic inflammatory disease and was commonly treated with immunosuppression. Other ILDs such as collagen vascular disease associated ILD and fibrotic hypersensitivity pneumonitis (HP) are still potentially treated with immunosuppression even though so called progressive fibrotic ILD of any association may benefit from anti-fibrotics [5]. It is essential that a distinction be made between IPF and these other ILDs

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