1  Introduction
Up to 20% of hospitalized coronavirus disease 2019 (COVID-19) patients are admitted to the intensive care unit (ICU) because of acute hypoxemic respiratory failure. [[1], [2], [3], [4]] These patients usually present with bilateral patchy ground glass opacities on computed tomography (CT) thorax fulfilling the definition for acute respiratory distress syndrome (ARDS). Often an atypical high compliance phenotype (L-type) is observed during mechanical ventilation in COVID-19 patients in contrast to mechanical ventilation characteristics typically seen in ARDS with low lung compliance phenotype (H -type). [5,6] During ICU stay the radiologic presentation of bilateral patchy ground glass opacities as present at admission often progress to consolidations with or without fibrotic characteristics [7]. Two earlier observed features may play a critical role in the severity of this disease: thromboembolic complications and early onset aspergillosis. The cumulative incidence of venous thromboembolism reported was 49% in COVID-19 patients admitted to the ICU [8]. Presumed pulmonary aspergillosis may be present in as much as 19% of ICU COVID-19 patients [9]. Since the physiology in COVID-19 related ARDS as well as its complications seems to differ from “typical’ ARDS, an insight into the pulmonary tissue pathology of this new infectious disease is of the utmost importance. The scarcely available pathological data in COVID-19 patients show diffuse alveolar damage, closely related to ARDS [[10], [11], [12]]. The clinical relevance of COVID-19-associated pulmonary aspergillosis (CAPA) as well as survival benefit with antifungal treatment and associated mortality are under debate since histopathological evidence of CAPA is not obtained [13]. We examined postmortem obtained lung tissue in seven patients, with COVID related ARDS who needed mechanical ventilation. The histopathologic findings, together with clinical features, radiological and microbiological findings are reported here. This report may contribute to new insights in the pathogeneses of COVID-19 as well as suggestions for treatment strategy.