Histopathologic survey on lung necropsy specimens of 15 patients who died from COVID-19: A large study from Iran with a high rate of anthracosis

Background: In the pandemic era of Coronavirus disease 19 (COVID-19), one of the most important issues is the nature of real pathological events that occur during disease course in different parts of the body. There are several ways to know more about COVID-related histopathological events,such as tissue sampling which means biopsy from the tissues of either livepeople or necropsy/autopsy of people who died from COVID-19. Methods: We conducted an original study for assessing histopathological findings of lung necropsy samples collected from 15 Iranian patients.The continuous variables were presented as mean and standard deviation, and for the qualitative data on histopathological findings, the percentage or qualitative scores (0 to +3) were used. Results: We found similar presentations of COVID-related histopathologic events regarding percentage and severity in pulmonary tissue, includinglymphocytic infiltrations, inflammatory infiltrations of septal and perivascular areas, desquamated type2 pneumocytes, hyaline membrane changes, fibrin material depositions, abnormal changes of alveolar capillaries, presence of megakaryocytes, PMN infiltrations, septal necrosis, microabscess formation and bacterial colony formation. Also, we found few interesting features which were not completely compatible with previous similar studies or newly reported by ours asa high percentage of anthracosis (86%: 13 patients) that was not clearly reported in other previous studies, also a lower percentage of microthrombotic vascular lung injuries (20%: 3 patients), and a higher percentage of viral cytopathic effects (27%: 4 patients). Conclusion: This article suggests a greater need for evaluatingthe autopsy samples of COVID-19 patients to provide better management strategies and propose the question of whether anthracosismay be a mortality risk factor in COVID-19 patients.