Imaging in idiopathic pulmonary fibrosis: diagnosis and mimics

Our plain-English summary of Imaging in idiopathic pulmonary fibrosis: diagnosis and mimics, by B. Hochhegger, E. Marchiori, M. Zanon, et al (Clinics, 2019).

The study

• Authors: B. Hochhegger, E. Marchiori, M. Zanon, A.S. Rubin, R. Fragomeni, S. Altmayer, C.R.R. Carvalho, B.G. Baldi
• Journal: Clinics
• Published: 2019;74:e225
• Type of article: Review
• Cited by: 37 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Idiopathic pulmonary fibrosis is a chronic disease of unknown etiology that usually has a progressive course and is commonly associated with a poor prognosis. The main symptoms of idiopathic pulmonary fibrosis, including progressive dyspnea and dry cough, are often nonspecific. Chest high-resolution computed tomography is the primary modality used in the initial assessment of patients with suspected idiopathic pulmonary fibrosis and may have considerable influence on subsequent management decisions. The main role of computed tomography is to distinguish chronic fibrosing lung diseases with a usual interstitial pneumonia pattern from those presenting with a non-usual interstitial pneumonia pattern, suggesting an alternative diagnosis when possible. A usual interstitial pneumonia pattern on chest tomography is characterized by the presence subpleural and basal predominance, reticular abnormality honeycombing with or without traction bronchiectasis, and the absence of features suggestive of an alternative diagnosis. Idiopathic pulmonary fibrosis can be diagnosed according to clinical and radiological criteria in approximately 66.6% of cases. Confirmation of an idiopathic pulmonary fibrosis diagnosis is challenging, requiring the exclusion of pulmonary fibroses with known causes, such as asbestosis, connective tissue diseases, drug exposure, chronic hypersensitivity pneumonitis, and other forms of idiopathic interstitial pneumonitis. The histopathological hallmark of usual interstitial pneumonia is a heterogeneous appearance, characterized by areas of fibrosis with scarring and honeycombing alternating with areas of less affected or normal parenchyma. The aim of this article was to review the clinical, radiological, and pathological features of idiopathic pulmonary fibrosis and of diseases that might mimic idiopathic pulmonary fibrosis presentation.

In plain English

This article was a narrative review, not an original study. The authors reviewed published literature on the clinical, CT scan and tissue (pathology) features of idiopathic pulmonary fibrosis (IPF), a scarring lung disease of unknown cause, and of diseases that can look like it, including asbestosis. Drawing on cited studies, they wrote that IPF can be diagnosed from clinical and radiological features alone in approximately 66.6% of cases. They also wrote that a confident CT diagnosis of the usual interstitial pneumonia (UIP) pattern is accurate in 80% to 95% of cases when compared with pathology. On asbestosis, the review stated that the main feature distinguishing it from IPF is a history of occupational exposure to asbestos, such as asbestos mining, shipbuilding and welding, with a link in time between exposure and symptoms. It stated that asbestosis typically shows a UIP pattern on CT and in tissue, that pleural plaques usually aid diagnosis, and that asbestos bodies must be present to confirm it in tissue. The authors concluded that diagnosing IPF is challenging and that multidisciplinary discussion improves diagnostic accuracy.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published literature, illustrated with CT and pathology images from individual patients
• Who was studied: No study population. The authors reviewed published literature on idiopathic pulmonary fibrosis and conditions that mimic it, including asbestosis, connective tissue diseases, drug exposure, chronic hypersensitivity pneumonitis and nonspecific interstitial pneumonia. The authors were based at institutions in Brazil.
• Exposure: No exposure was studied. Asbestos exposure is discussed as the cause of asbestosis, one of the diseases that can mimic IPF. The examples of occupational exposure given are asbestos mining, shipbuilding and welding. No fiber types or doses are given.
• Main results:
  • Review statement (citing guidelines): CT criteria for a UIP diagnosis include honeycombing, with or without peripheral traction bronchiectasis or bronchiolectasis, in a basal and subpleural distribution.
  • Review statement (citing an earlier study): in approximately 66.6% of cases, IPF can be diagnosed from clinical and radiological features alone.
  • Review statement (citing literature): a confident CT diagnosis of UIP is accurate in 80% to 95% of cases, using pathology as the reference.
  • Review statement: the main feature distinguishing asbestosis from IPF is a history of occupational exposure to asbestos. Establishing a link in time between the exposure and the start of symptoms is described as essential.
  • Review statement: asbestosis typically has a UIP pattern on tissue examination and on CT, and pleural plaques usually aid in the diagnosis.
  • Review statement: under the microscope, features that help tell asbestosis apart from UIP are collagen fibrosis without fibroblastic foci and only a mild inflammatory infiltrate. Asbestos bodies must be present to confirm the tissue diagnosis of asbestosis.
• The authors' conclusion: The authors concluded that diagnosing IPF is challenging, and that multidisciplinary discussion among physicians, radiologists and pathologists with interstitial lung disease expertise improves diagnostic accuracy.

Topics

Medical terms in this study, explained in our Lexicon: Idiopathic, Pulmonary Fibrosis, Etiology, Prognosis, Dyspnea, Interstitial, Honeycombing, Pneumonitis.

Related studies

• Clinical and radiological criteria for the differential diagnosis between asbestosis and idiopathic pulmonary fibrosis: Application in two cases — A. Stufano, A. Scardapane, et al. (2021)
• Radiological characteristics, histological features and clinical outcomes of lung cancer patients with coexistent idiopathic pulmonary fibrosis — K.A. Khan, M.P. Kennedy, et al. (2015)
• The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis — M. Akira, K. Morinaga (2016)
• Labial salivary gland assessment in idiopathic pulmonary fibrosis patients with sicca symptoms — M. Bawazir, S. Cha, et al. (2021)
• The Its Not JUST Idiopathic pulmonary fibrosis Study (INJUSTIS): description of the protocol for a multicentre prospective observational cohort study identifying biomarkers of progressive fibrotic lung disease — F. Khan, I. Stewart, et al. (2019)
• Differential diagnosis of usual interstitial pneumonia: when is it truly idiopathic? — W.A. Wuyts, A. Cavazza, et al. (2014)

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