Since December 2019, the global burden of the COVID-19 pandemic has increased rapidly and has impacted nearly every country in the world, affecting those who are elderly or with underlying comorbidities or immunocompromised states. Aim of this systematic review is to summarize lung histopathological characteristics of COVID-19, not only for diagnostic purpose but also to evaluate changes that can reflect pathophysiological pathways that can inform clinicians of useful treatment strategies. We identified following histopathological changes among our patients:: hyaline membranes; endothelial cells/ interstitial cells involvement; alveolar cells, type I pneumocytes/ type II pneumocytes involvement; interstitial and/ or alveolar edema; evidence of hemorrhage, of inflammatory cells, evidence of microthrombi; evidence of fibrin deposition and of viral infection in the tissue samples. The scenario with proliferative cell desquamation is typical of Acute Respiratory Distress Syndrome (ARDS) that can be classified as diffuse alveolar damage (DAD) and not DAD-ARDS. The proposed pathological mechanism concerns the role of both innate and adaptive components of the immune system. COVID-19 lethal cases present themselves as a heterogeneous disease, characterized by the different simultaneous presence of different histological findings, which reflect histological phases with corresponding different pathological pathways (epithelial, vascular and fibrotic changes), in the same patient.

中文翻译：

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COVID-19 疾病的肺组织病理学结果——系统评价


自 2019 年 12 月以来，COVID-19 大流行的全球负担迅速增加，几乎影响到世界上每个国家，影响到老年人或患有潜在合并症或免疫功能低下的人。本系统综述的目的是总结 COVID-19 的肺部组织病理学特征，不仅用于诊断目的，还评估可以反映病理生理学途径的变化，从而为临床医生提供有用的治疗策略。我们在患者中发现了以下组织病理学变化：：透明膜；内皮细胞/间质细胞参与；肺泡细胞、I 型肺细胞/ II 型肺细胞受累；间质和/或肺泡水肿；出血、炎症细胞、微血栓的证据；组织样本中纤维蛋白沉积和病毒感染的证据。增殖细胞脱落的情况是急性呼吸窘迫综合征 (ARDS) 的典型情况，可归类为弥漫性肺泡损伤 (DAD)，而不是 DAD-ARDS。所提出的病理机制涉及免疫系统先天和适应性成分的作用。 COVID-19致死病例表现为一种异质性疾病，其特征是同一患者同时存在不同的组织学结果，反映了具有相应不同病理途径（上皮、血管和纤维化变化）的组织学阶段。