The histopathological findings of the lung in covid-19 patients
The main pulmonary finding was diffuse alveolar damage in the acute or organising phases, rendering focal pulmonary microthrombi. The primary pathology observed was diffuse alveolar damage, with virus existing in the pneumocytes and tracheal epithelium. Microthrombi were rare and endotheliitis was not identified. Immunohistochemistry staining was done on formalin fixed, paraffin-embedded 5-µm sections following citrate pH 6·0 antigen retrieval, endogenous biotin, and peroxidase block. Immunohistochemistry for SARS-CoV-2 was completed using a monoclonal antibody to the spike protein. Images were visualised and captured with a digital camera mounted on a Nikon Eclipse 80i microscope. Other series displayed evidence of diffuse alveolar damage and the presence of endothelial injury. Tissue quantitative RT-PCR (RT-qPCR) was used to identify the RNA of the virus. Autopsy material was fixed in 10% neutral buffered formalin and submitted for standard processing with haematoxylin and eosin staining. Focal pulmonary micro thrombi were identified. Micro thrombi in the trachea was observed. Microscopic involvement by grossly observed pulmonary emboli was seen. The finding also observed pulmonary oedema, prominent reactive type 2 pneumocytes, intra-alveolar fibrin, and hyaline membranes. The hypothesis that lung injury might occur in COVID-19 patients before symptom beginning is confirming by evidence of abnormal pulmonary CT findings in asymptomatic patients.