Morphological characteristics of lung tissue in two cases with critical corona virus disease 2019

Objective To observe the morphological features of lungs in patients with critical 2019 corona virus disease (COVID-19), and to analyze the clinical-pathological relationship. Methods Two critical patients with COVID-19 who died in Beijing You'an Hospital affiliated to Capital Medical University on February 13 and 14, 2020, respectively were examined by bilateral lungs biopsy. The obtained samples were dehydrated, paraffin embedded, sectioned, stained with hematoxylin-eosin as routine methods, and then observed under light microscope. Results The pulmonary morphology changes of patients with COVID-19 showed diffuse alveolar damage. Case one was an elderly patient with underlying diseases and his lesions were mainly exudation and hyaline membrane formation, which showed an acute exudation stage of diffuse alveolar damage. Case two was a patient without underlying diseases and his pathological changes were diffuse inflammatory cell infiltration, extensive fibrosis of alveolar wall, filling of necrotizing inflammatory cellulosic exudate in alveolar airspace, extensive destruction of alveoli and pulmonary consolidation, which was characterized by organized stage of diffuse alveolar damage complicated with bacterial pneumonia. The injury of paracronchial submucosal gland was not observed in the two patients. Conclusions Diffused alveolar damage is the main pathological feature of critical COVID-19. Diffused alveolar damage can induce or aggravate the underlying diseases of elderly patients in the early stage. Extensive destruction of alveoli, pulmonary consolidation and secondary infection are the main causes of respiratory failure in the late stage. Key words: Coronavirus infections; Pneumonia; Pathology; 2019-nCoV; COVID-19; Lung tissue