Diffuse alveolar damage and thrombotic microangiopathy are the main histopathological findings in lung tissue biopsy samples of COVID-19 patients

Since the outbreak of the novel coronavirus disease-2019 (COVID-19) in December 2019, limited studies have investigated the histopathologic findings of patients infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This study was conducted on 31 deceased patients who were hospitalized for COVID-19 in a tertiary hospital in Tehran, Iran. A total of 52 postmortem tissue biopsy samples were obtained from the lungs and liver of decedents. Clinical characteristics, laboratory data, and microscopic features were evaluated. Reverse transcription polymerase chain reaction (RT-PCR) assay for SARS-CoV-2 was performed on specimens obtained from nasopharyngeal swabs and tissue biopsies. The median age of deceased patients was 66 years (range, 30–87 years) and 25 decedents (81 %) were male. The average interval from symptom onset to death was 13 days (range, 6–34 days). On histopathologic examination of the lung specimens, diffuse alveolar damage and thrombotic microangiopathy were the most common findings (80 % and 60 %, respectively). Liver specimens mainly showed macrovesicular steatosis, portal lymphoplasmacytic inflammation and passive congestion. No definitive viral inclusions were observed in any of the specimens. In addition, 92 % of lung tissue samples tested positive for SARS-CoV-2 by RT-PCR. Further studies are needed to investigate whether SARS-CoV-2 causes direct cytopathic changes in various organs of the human body.