Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

: 2020  |  Volume : 30  |  Issue : 4  |  Page : 415--419

COVID-19 pneumonia-residual changes on CT scan are they all fibrosis

Anirudh Kohli 
 Breach Candy Hospital Trust, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Anirudh Kohli
Breach Candy Hospital Trust, Mumbai, Maharashtra

How to cite this article:
Kohli A. COVID-19 pneumonia-residual changes on CT scan are they all fibrosis.Indian J Radiol Imaging 2020;30:415-419

How to cite this URL:
Kohli A. COVID-19 pneumonia-residual changes on CT scan are they all fibrosis. Indian J Radiol Imaging [serial online] 2020 [cited 2021 Jan 15 ];30:415-419
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Full Text

COVID-19 pneumonia causes diffuse alveolar damage. This passes through three stages, an initial exudative phase where there is minimal exudation of fluid into the alveoli. As a result, imaging appearances will be negative or subtle abnormalities off ground glass will be seen. Subsequently, with increased exudation into the alveoli it passes into the next stage, an inflammatory stage. Depending on the extent of alveolar exudation the appearances on imaging are ground glass densities, consolidation or a combination of these. Finally, the diffuse alveolar damage passes into a reparative phase where there is proliferation of epithelial cells and fibroblasts with collagen deposition. On imaging the appearances in this stage are off an organising pneumonia. The brunt of the disease process of COVID-19 is in the interstium, thus in the peripheral subpleural and peribronchovascular regions. As the organising pneumonia clears, there are reticular opacities in the subpleural and peribronchial regions. Often there is a subpleural curvilinear line and residual peribronchovascular and subpleural reticular abnormalities which resemble fibrosis seen in ILD. This is the main consideration, are these to be reported as fibrosis? this is important as fibrosis is irreversible. However, with time sometimes even 4-6 months later most of these abnormalities clear up, even the subpleural curvilinear lines. Only very few cases of persistent reticular abnormalities have been seen. Time will tell whether these are also really fibrosis or slow resolving organising pneumonia since these may clear with time.

To call these fibrosis may be a bit premature.

Appended are a sampling of cases demonstrating progression and regression patterns in COVID-19 pneumonia.[INLINE:1][INLINE:2][INLINE:3][INLINE:4][INLINE:5][INLINE:6][INLINE:7][INLINE:8][INLINE:9][INLINE:10][INLINE:11][INLINE:12][INLINE:13][INLINE:14][INLINE:15]