Clinicopathological Outlines of Post-COVID-19 Pulmonary Fibrosis Compared with Idiopathic Pulmonary Fibrosis

Abstract

This review brings together the current knowledge regarding the risk factors and the clinical, radiologic, and histological features of both post-COVID-19 pulmonary fibrosis (PCPF) and idiopathic pulmonary fibrosis (IPF), describing the similarities and the disparities between these two diseases, using numerous databases to identify relevant articles published in English through October 2022. This review would help clinicians, pathologists, and researchers make an accurate diagnosis, which can help identify the group of patients selected for anti-fibrotic therapies and future therapeutic perspectives.

Keywords: idiopathic pulmonary fibrosis; interstitial lung disease; post-COVID-19 pulmonary fibrosis; pulmonary fibrosis.

Figure 1

Courtesy of Dr Oana Cristina Arghir, who provided images of post-COVID-19 pulmonary fibrosis from Pneumology Hospital of Constanta, Romania. Thoracic CT scan of a patient with PCF, one year after the acute episode, showing subpleural and peribronchovascular reticular opacities, traction bronchiectasis (a), and GGO bilateral and fibrotic lines predominantly in the upper lobes (b), in a 77-year-old male, with history of severe COVID-19 in October 2021 and PCPF in October 2022.

Figure 2

Courtesy of Dr Ariadna Petronela Fildan, who provided images of IPF from Pneumology Hospital of Constanta, Romania. Thoracic CT scan of a patient with IPF showing honeycombing and reticular opacities with the basal and subpleural distribution in a 73-year-old male smoker, with exposure to environmental pollutants (a), with idiopathic pulmonary fibrosis (b), who died in 2017, 3 years after the diagnosis.

Figure 3

Courtesy of Dr Mariana Deacu, who provided images of post-COVID-19 pulmonary fibrosis from “St. Andrew” Emergency County Hospital of Constanta, Romania. (a) Macroscopic and (b) microscopic aspect of the lung in a 55-year-old male patient with COVID-19 interstitial pneumonia in the fibrosing stage, whose autopsy was performed three months after SARS-CoV-2 infection, showing architectural disorder caused by excessive extracellular matrix, dense collagen deposition, and diffuse thickening of alveolar walls. HE ×40.

Figure 4

Courtesy of Dr Mariana Deacu, who provided images of post-COVID-19 pulmonary fibrosis from “St. Andrew” Emergency County Hospital of Constanta, Romania. Microscopic view of the lung in a 68-year-old patient with COVID-19, whose necropsy was performed five weeks after SARS-CoV-2 infection, showing (a) interstitial inflammatory infiltrate reduced and (b) chronic bronchiolitis. HE ×100.

Figure 5

Courtesy of Dr Mariana Deacu, who provided images of post-COVID-19 pulmonary fibrosis from “St. Andrew” Emergency County Hospital of Constanta, Romania. (a) Macroscopic and (b) microscopic aspects of the lung in a 62-year-old patient showing thrombosis, whose necropsy was performed three weeks after SARS-CoV-2 infection, showing pulmonary vascular endothelitis and angiogenetic alterations. HE ×40.

Figure 6

Courtesy of Dr Mariana Deacu, who provided images of post-COVID-19 pulmonary fibrosis from “St. Andrew” Emergency County Hospital of Constanta, Romania. Microscopic view of the lung in a 68-year-old patient, whose necropsy was performed eight months after SARS-CoV-2 infection, showing (a) type II pneumocyte hyperplasia and reactive pneumocytes, (b) alveolar wall thickening, and myofibroblast proliferation. HE ×100.

Figure 7

Courtesy of Dr Angela-Ștefania Marghescu, who provided images of IPF from Pneumology Institute “Marius Nasta” Bucharest, Romania. (a) Spatial variability, with normal lung parenchyma mixed with fibrotic areas (fibroblastic focus); HE ×40. (b) Interstitial fibrosis with architectural distortion and cystic changes in the pulmonary parenchyma; HE ×40, in a 62-year-old woman, whose necropsy was performed three months after SARS-CoV-2 infection, with marked pulmonary fibrosis.