Organizing pneumonia and COVID-19: A report of two cases.

Organizing pneumonia (OP) is a sub-acute process of pulmonary tissue repair secondary to lung injury, defined histopathologically by intra-alveolar buds of granulation tissue within the lumen of distal pulmonary airspaces. It can be either cryptogenic or secondary (SOP) to different clinical conditions, namely infections. Despite being nonspecific, its diagnosis can be made by the association of clinical and imaging criteria. We report two cases of OP associated to SARS-CoV-2 pneumonia, admitted at a Portuguese tertiary hospital unit dedicated to COVID-19. Both patients presented with severe respiratory failure with need of invasive mechanical ventilation. After initial recovery, there was worsening of dyspnea and hypoxemic respiratory failure with increase in inflammatory markers. Chest CT revealed an OP pattern. Other conditions such as superinfection, auto-immune disease and iatrogenic etiology, were excluded and corticotherapy at a dose of 1 mg/kg/day was administered. Chest CT follow up of both our patients showed complete resolution of OP pattern, with mild to moderate residual pulmonary fibrosis without honeycombing. There is no OP to SARS-CoV-2 case series yet published describing the progress of patients after corticotherapy, although the association between systemic corticosteroids and lower all-cause mortality in patients with COVID-19 has been recently established. It is possible that, as has been described with other viruses, OP secondary to SARS-CoV-2 represents an immunological process after initial infection, presenting with elevation of inflammatory markers and cytokines storm in the bloodstream and lung tissue, which may explain the favorable response to corticosteroids.