Pathological diagnosis of Coronavirus-related nephropathy: insight from postmortem studies.

A novel coronavirus pneumonia first occurred in Wuhan, China in early December 2019; the causative agent was identified and named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the World Health Organization (WHO), and the resulting disease termed coronavirus disease 2019 (COVID-19), according to the WHO coronavirus disease situation reports. This condition has spread rapidly all over the world and caused more than 125 million cases globally, with more than 2 million related deaths. Two previous outbreaks due to zoonotic coronaviruses have occurred in the last 20 years, namely the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV), causing high morbidity and mortality in human populations upon crossing the species barriers. SARS-CoV-2, SARS-CoV, and MERS-CoV show several similarities in pathogenicity and clinical presentations, the latter ranging from asymptomatic infection to severe acute respiratory distress syndrome (ARDS) and multiorgan impairment. Acute kidney injury (AKI) has been commonly reported in patients with CoV infections; therefore, pathological analysis of renal parenchyma in these patients has been carried out in order to improve knowledge about underlying mechanisms. Viral infection has been demonstrated in the renal tubular epithelial cells by electron microscopy (EM), immunohistochemistry (IHC), and in situ hybridization (ISH), although with conflicting results. Light microscopy (LM) changes have been described in the renal parenchyma primarily in the form of acute renal tubular damage, possibly due to direct viral cytopathic effect and immune-mediated mechanisms such as cytokine storm syndrome. In this review, we describe and discuss the spectrum of histological, ultrastructural, and molecular findings in SARS-CoV, MERS-CoV, and SARS-CoV-2-related renal pathology obtained from postmortem studies, as well as intrinsic limitations and pitfalls of current diagnostic techniques.

SARS-CoV-2-related lung pathology: macroscopic and histologic features and their clinical implications.

The ongoing global Coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), has been posing challenges to proper patients' management. Lungs are the first, and often the most affected organ by SARS-CoV-2; viral infection involves and damages both epithelial and vascular compartments, sometimes leading to severe and even fatal acute respiratory distress syndrome. Histopathological findings, mainly from post-mortem examination of COVID-19 deceased patients, have been increasingly published in the last few months, helping to elucidate the sequence of events resulting in organ injury and the complex multifactorial pathogenesis of this novel disease. A multidisciplinary approach to autopsy, including light microscopy examination along with the detection of viral proteins and/or RNA in tissue samples through ancillary techniques, provided crucial information on the mechanisms underlying the often-heterogeneous clinical picture of COVID-19.