Post-COVID-19 Pulmonary Fibrosis: A Comprehensive Review and Comparison with Non-COVID-19 Cases

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architecture and reducing elasticity.As ECM buildup progresses, lung remodeling leads to architectural changes that impair gas exchange and decrease lung compliance, ultimately limiting respiratory function.The process reflects a failure in resolving tissue repair, resulting in chronic, progressive scarring instead of normal restoration of lung structure.Persistent injury to type II alveolar epithelial cells in pulmonary fibrosis leads to the release of fibrogenic cytokines and growth factors, which play a central role in promoting fibroblast activation and ECM deposition.This release of signaling molecules perpetuates the fibrotic process IntroductIonThe coronavirus disease 2019 (COVID-19) pandemic has resulted in an unprecedented impact on global health.As of today, millions of survivors face a spectrum of long-term complications, among which pulmonary fibrosis has emerged as a significant concern. 1 COVID-19 primarily spreads through respiratory droplets, with the virus entering the lungs via inhalation.Once in the respiratory tract, it infects the lung parenchyma, leading to severe COVID-19 pneumonia in about 14% of cases.Studies show that between 15.6 and 31% of COVID-19 patients may progress to acute respiratory distress syndrome (ARDS).ARDS is marked by a rapid onset of severe shortness of breath (dyspnea), low oxygen levels in the blood (hypoxemia), and bilateral diffuse infiltrates visible on radiographic imaging, indicating widespread inflammation and damage to the lungs. 2 Pulmonary fibrosis, involving permanent scarring of the lung tissue, can impair respiratory function and, in severe cases, lead to respiratory failure.In light of increasing cases of post-COVID pulmonary fibrosis, this review aims to explore its mechanisms, diagnostic features, and management options.We also compare COVID-19-related fibrosis with fibrosis due to other causes, such as idiopathic pulmonary fibrosis (IPF), highlighting similarities and distinctions in pathology, clinical presentation, and treatment. PathoPhysIology o f Pulmonary fIbrosIsPulmonary fibrosis results from an abnormal wound-healing response to lung injury, characterized by the excessive activation of fibroblasts and myofibroblasts, which produce high levels of extracellular matrix (ECM) proteins such as collagen.