Coronavirus disease 2019 morbid pulmonary pathology: What did we learn from autopsy examinations?

Despite the rapidly expanding data on clinical, epidemiological and radiological aspects of coronavirus disease 2019 (COVID-19), little is known about the disease's pathological aspects. The scarcity of pathological data on COVID-19 can be explained by the limited autopsy procedures performed on deceased patients.

This work aims to review and summarize the pulmonary pathological findings observed in COIVD-19 deceased individuals based on recent case series reports published in English up to September 2020.

A search in Google Scholar, PubMed^Ò, MEDLINE^Ò, and Scopus was performed using the keywords "autopsy and COVID-19," "postmortem and COVID-19," and "pulmonary/lung pathology and COVID-19."

Pulmonary autopsy hallmark findings of COVID-19 cases demonstrate the presence of diffuse alveolar damage. The presence of pulmonary thrombi was reported in the majority of patients. Cellular alterations included type 2 pneumocyte hyperplasia, inflammatory cell infiltrates predominantly by lymphocytes, other mononuclear cells, and neutrophils as evident by their specific immunohistochemical markers. Electron microscopy confirmed the presence of virus particles in different cell types, including types 1 and 2 pneumocytes.

The few emerging autopsy reports have substantially contributed towards our understanding of COVID-19 pulmonary histopathological aspects. COVID-19 caused acute severe respiratory manifestations that are the leading cause of morbidity and mortality in infected patients. More studies and research are needed to understand the inflammatory processes and histopathological changes associated with COVID-19 in African populations.

Postmortem investigations advance important mechanistic knowledge on COVID-19 pathophysiology and clinical outcomes and could facilitate provisions for targeted therapies.