Histopathological features in fatal COVID-19 acute respiratory distress syndrome.

BACKGROUND

COVID-19 acute respiratory distress syndrome (ARDS) shares the common histological hallmarks with other forms of ARDS. However, the chronology of the histological lesions has not been well established.

OBJECTIVE

To describe the chronological histopathological alterations in the lungs of patients with COVID-19 related ARDS.

DESIGN

A prospective cohort study was carried out.

SETTING

Intensive Care Unit of a tertiary hospital.

PATIENTS

The first 22 consecutive COVID-19 deaths.

MEASUREMENTS

Lung biopsies and histopathological analyses were performed in deceased patients with COVID-19 related ARDS. Clinical data and patient course were evaluated.

RESULTS

The median patient age was 66 [63-74] years; 73% were males. The median duration of mechanical ventilation was 17 [8-24] days. COVID-19 induced pulmonary injury was characterized by an exudative phase in the first week of the disease, followed by a proliferative/organizing phase in the second and third weeks, and finally an end-stage fibrosis phase after the third week. Viral RNA and proteins were detected in pneumocytes and macrophages in a very early stage of the disease, and were no longer detected after the second week.

LIMITATION

Limited sample size.

CONCLUSIONS

The chronological evolution of COVID-19 lung histopathological lesions seems to be similar to that seen in other forms of ARDS. In particular, lung lesions consistent with potentially corticosteroid-sensitive lesions are seen.