Histopathological Analysis of Lung Infections during Pre and Post COVID-19 Eras: Insights from a Four-Year Autopsy Study at a Tertiary Care Hospital in Tirunelveli, Tamil Nadu, India
Authors: Muthureddy Yogambal , Kandasamy Mahalakshmi , Pillai Selvam Abathu Katha , Kalyanasundaram Swaminathan 
Published: August 2023

Introduction: Autopsies are routinely useful in establishing the cause and time of death. The Coronavirus Disease-2019 (COVID-19), a pandemic viral infectious disease, has affected many countries worldwide. In developing countries like India, infectious lung pathology has been a significant cause of death even before the COVID-19 era. However, the emergence of COVID-19, there has been an increase in lung infections due to factors such as prolonged hospital stays, assisted ventilation, lung damage, and immune suppression, affecting both morbid patients and survivors. Aim: To describe the histopathological spectrum of infective lesions of lung in autopsy during Pre COVID-19 and COVID-19 era in a tertiary care hospital of Tirunelveli, Tamil Nadu, India. Materials and Methods: This cross-sectional study was conducted in the Department of Pathology at Tirunelveli Medical College, Tirunelveli, Tamil Nadu, India, between January 2018 and December 2021. Data including age, sex, COVID-19 status, clinical history, histomorphological patterns, and identification of infectious agents, were collected from clinico-pathological and autopsy documents. A total of 627 lung specimens were available, with 41 specimens being autolyzed, leaving 586 specimens for inclusion in the study. Gross morphology and microscopic features were documented, and diagnoses were made based on these findings. Results: The study included a total of 586 specimens, of which 76 (12.9%) were reported as infective pathology. Among these cases, 29 (38.1%) cases were reported in the pre COVID19 period, and 47 (61.9%) were reported during the COVID19 period. Of the 76 cases, 41 (53.95%) were male, and 35 (46.05%) were female. The number of cases reported during the post COVID-19 period (47 cases, 61.84%) was higher than the number reported during the pre COVID-19 period (29 cases, 38.16%). In both periods, the majority of cases (10 cases, 13.1% in the pre COVID-19 period; 13 cases, (17.1%) in the post COVID-19 period) were observed in individuals aged 60 years and above, followed by those in the age group of 50 to 59 years (7 cases, 9.2%). Similarly, in the pre COVID-19 period; 10 cases, 13.2% in the post COVID-19 period). Among the 76 cases, interstitial pneumonia (9 cases, 11.8%) was the most common finding in the pre COVID-19 period, followed by bronchopneumonia (seven cases, 9.2%). In the COVID-19 period, Tuberculosis (TB) was the most common finding (17 cases, 22.4%), followed by pneumonia with consolidation (10 cases, 13.2%). Additionally, the number of cases diagnosed with pulmonary TB during the COVID-19 period (17 cases, 22.4%) was higher than that during the pre COVID-19 period (6 cases, 7.9%). During the post COVID-19 period, there has been a drastic increase in the number of pneumonia cases compared to the pre COVID-19 era, and this increase is statistically significant with a p-value of 0.04. Conclusion: Pneumonia (lobar pneumonia, interstitial pneumonia, and bronchopneumonia) is the most common histopathological lung lesion in the present study. Compare to pre COVID-19 era, there is increased number of infective lesions during COVID-19 era. There was a drastic increase in pathological findings of Kochs lesion during COVID-19 era.