Clinicopathological correlation in fatal COVID-19 infection using postmortem minimally invasive tissue sampling: The first case series from India

Introduction: The COVID-19 pandemic began in China in December 2019 India is the second most affected country, as of November 2020 with more than 8 5 million cases COVID-19 infection primarily involves the lung with the severity of illness varying from influenza-like illness to acute respiratory distress syndrome Other organs have also been found to be variably affected Studies evaluating the histopathological changes of COVID-19 are critical in providing a better understanding of the disease pathophysiology and guiding treatment Minimally invasive biopsy techniques (MITS/B) provide an easy and suitable alternative to complete autopsies In this prospective single-center study, we present the histopathological examination of 37 patients who died with complications of COVID-19 Materials and methods: This was an observational study conducted in the Intensive Care Unit of JPN Trauma Centre AIIMS A total of 37 patients who died of COVID-19 were enrolled in the study Postmortem percutaneous biopsies were taken with the help of surface landmarking/ultrasonography guidance from lung, heart, liver, and kidneys;after obtaining ethical consent The biopsy samples were then stained with hematoxylin and eosin stain Immunohistochemistry (IHC) was performed using CD61 and CD163 in all lung cores The SARS-CoV-2 virus was detected using IHC with primary antibodies in selected samples Details regarding demographics, clinical parameters, hospital course, treatment details, and laboratory investigations were also collected for clinical correlation Results: A total of 37 patients underwent post-mortem minimally invasive tissue sampling Mean age of the patients was 48 7years and 59 5% of them were males Respiratory failure was the most common complication seen in 97 3% Lung histopathology showed acute lung injury and diffuse alveolar damage in 78% patients Associated bronchopneumonia was seen in 37 5% patients and scattered microthrombi were visualised in 21% patients Immunostaining with CD61 and CD163 highlighted megakaryocytes, and increased macrophages in all samples Immunopositivity for SARS-CoV-2 was observed in Type II pneumocytes Acute tubular injury with epithelial vacuolization was seen in 46% of the renal biopsies but none of them showed evidence of microvascular thrombosis 71% of the liver tissue cores showed evidence of Kupfer cell hyperplasia 27 5% had evidence of submassive hepatic necrosis and 14% had features of acute on chronic liver failure All the heart biopsies showed nonspecific features such as hypertrophy with nucleomegaly with no evidence of myocardial necrosis in any of the samples Discussions: Minimally invasive autopsies (MIA) or MITS/B are a simplified method of conducting postmortem sampling, originally devised to investigate the causes of death in low-resource settings Due to the potential risks associated with conducting traditional postmortem examinations in COVID-19 patients, this method has been adopted to study morbid pathological changes in COVID-19 patients The typical findings described in pulmonary histopathology of COVID-19 patients include epithelial, vascular, fibrotic, and other changes The epithelial changes described include diffuse alveolar damage with or without hyaline membranes, metaplasia of alveolar epithelium, desquamation/reactive hyperplasia of pneumocytes, viral cytopathic changes, and multinucleated giant cells Common vascular changes include capillary congestion, thrombosis in microvasculatures, alveolar hemorrhage, capillary changes (proliferation, thickening, fibrin deposition, endothelial detachment), peri- or intravascular inflammatory infiltrates In our series, the most common histopathological pattern seen on lung samples was DAD (diffuse alveolar damage), with nearly equal numbers of patients showing DAD in the acute exudative phase and organizing phase The incidence of vascular changes were only 21%, which was less than that reported Several factors could have contributed to this observation including regular use of anticoagulants in the coh rt as a part of national policies, lower thrombotic complications in the population studied due to genetic or climatic factors Histopathological examination of the liver in COVID-19 patients had typically revealed mild steatosis, focal hepatic necrosis, Kupffer cell hyperplasia, and sinusoidal dilatation as reported in the literature In our series, the most common features identified include Kupffer cell hypertrophy in 21 (72 41%) patients, acute submassive hepatic necrosis (27 5%) followed by acute on chronic liver failure (13 7%) in a background of chronic liver diseases, features of NCPF (10 3%) and cholestasis (24%) Though in our cohort of liver biopsies, hepatic lobular inflammatory cell infiltrates were not prominent, changes of hepatocyte degeneration as ballooning, acidophil bodies, MDBs (Mallory-Denk bodies), and microvesicular steatosis were prominent Lack of inflammatory cell infiltrates in the liver has been described in earlier reports on fatal COVID-19 infections Our findings disagree with the observation of Sonzogni et al that the liver is not a primary target of COVID- 19 infection and only vascular changes in the liver are observed In this cohort, we identified substantial histological changes of hepatocyte necrosis, degeneration, Kupffer cell hypertrophy, micro, and macrovesicular steatosis, more than the vascular changes Renal histopathology in COVID-19 is reported to show changes including prominently acute tubular injury (more prominent in the proximal tubules), arteriosclerosis, or glomerulosclerosis (both as features of underlying comorbid conditions like hypertension), focal segmental glomerulosclerosis with a collapsing phenotype, and tubulointerstitial inflammation Renal vascular changes reported are relatively less common and include fibrin thrombi, thrombotic angiopathy, and lymphocytic endothelitis In our cohort of patients, the most common finding on renal histopathology was acute tubular injury and preexisting renal conditions were only evident in 18% None of the cases showed significant vascular changes Conclusion: The most common finding in this cohort is the diffuse alveolar damage with a demonstration of SARS-CoV-2 protein in the acute phase of DAD Microvascular thrombi were rarely identified in the lung, liver, and kidney Substantial hepatocyte necrosis, hepatocyte degeneration, Kupffer cell hypertrophy, micro, and macrovesicular steatosis unrelated to microvascular thrombi suggests that the liver might be a primary target of COVID-19 This study highlights the importance of MITS/B in better understanding the pathological changes associated with COVID-19