Long-term Lung Abnormalities Associated with COVID-19 Pneumonia

Abstract

In the 3rd year of the SARS-CoV-2 pandemic, much has been learned about the long-term effects of COVID-19 pneumonia on the lungs. Approximately one-third of patients with moderate-to-severe pneumonia, especially those requiring intensive care therapy or mechanical ventilation, have residual abnormalities at chest CT 1 year after presentation. Abnormalities range from parenchymal bands to bronchial dilation to frank fibrosis. Less is known about the long-term pulmonary vascular sequelae, but there appears to be a persistent, increased risk of venothromboembolic events in a small cohort of patients. Finally, the associated histologic abnormalities resulting from SARS-CoV-2 infection are similar to those seen in patients with other causes of acute lung injury.

Graphical abstract

Figure 1:

Images in a 63-year-old man with residual lung abnormalities from SARS-CoV-2 infection. (A) Contrast-enhanced axial CT image at presentation shows peripheral and peribronchial ground-glass opacity and consolidation along with perilobular thickening (arrows). (B) Unenhanced axial CT image 1 year later shows patchy residual ground-glass opacity, persistent perilobular thickening (arrows), and mild bronchial dilation (arrowheads) in areas of ground-glass opacity.

Figure 2:

Images in a 57-year-old man with fibrosis resulting from SARS-CoV-2 infection. (A) Contrast-enhanced axial CT image at presentation shows peripheral predominant ground-glass opacity with a small amount of consolidation. (B) Unenhanced axial CT image 3 months later shows marked clearing of ground-glass opacity but development of reticulation and mild bronchial dilation (arrow). (C) Unenhanced axial CT image 6 months after infection shows further decrease of ground-glass opacity and a lesser extent of reticulation. The area of bronchial dilation in the left upper lobe has resolved, although there is a small peripheral area of traction bronchiectasis (arrow).

Figure 3:

Images in a 56-year-old man with fibrosis resulting from SARS-CoV-2 infection. (A) Contrast-enhanced axial CT image early during infection shows extensive ground-glass opacity with posterior and peripheral predominant consolidation and some areas of crazy paving. (B) Unenhanced axial CT image from 10 months later shows lower lobe predominant reticulation, traction bronchiectasis, and ground-glass opacity with lower lobe volume loss.

Figure 4:

Image in a 74-year-old man with history of SARS-CoV-2 infection. Unenhanced axial CT image 5 months after acute infection shows bilateral residual peripheral ground-glass opacity and bandlike opacities. Varicoid traction bronchiectasis and bronchiolectasis occurs within areas of reticulation and architectural distortion, in keeping with fibrosis (arrows).

Figure 5:

Images in a 77-year-old woman hospitalized with acute respiratory distress syndrome resulting from SARS-CoV-2 infection. (A) Unenhanced axial CT image during acute infection and mechanical ventilation shows typical findings of alveolar damage, with dependent consolidation and ground-glass opacity throughout the remainder of the lungs. Varicoid bronchial dilation and an air cyst have developed within the anterior right lung (arrow). (B, C) Unenhanced axial CT images 10 months after infection show anterior predominant varicoid bronchiectasis (arrows), slightly decreased in severity and accompanied by reticulation and architectural distortion. A background of residual ground-glass opacity, peripheral parenchymal bands, and reticulation is also present.

Figure 6:

Images in a 51-year-old woman with history of SARS-CoV-2 infection, noninvasive positive pressure ventilation, and chronic dyspnea requiring home oxygen therapy. (A) Contrast-enhanced axial CT image during acute infection shows bilateral ground-glass opacity with peripheral predominance (arrows). (B) Contrast-enhanced axial CT image after discharge, 2 months after presentation, shows diffuse ground-glass opacity and architectural distortion with diffuse varicoid bronchial dilation (arrows). (C) Unenhanced axial CT image 6 months after presentation shows decrease in ground-glass opacity but persistent diffuse varicoid bronchiectasis (arrows); a small left pneumothorax is also present.

Figure 7:

Images in a 58-year-old woman with history of SARS-CoV-2 infection, ongoing dyspnea after infection, and history of sleep apnea. (A) Unenhanced axial CT image at full inspiration performed 2 years after acute infection shows subtle diffuse mosaic attenuation. (B) Paired expiratory axial CT image shows extensive lobular and regional low attenuation indicative of air trapping (arrows).

Figure 8:

Histologic image (hematoxylin and eosin stain, 200× magnification) shows recanalized pulmonary arteriole with neolumen formation. This finding was observed in an explanted lung 4 months after acute COVID-19.

Figure 9:

Histologic image (hematoxylin and eosin stain, 200× magnification) of alveolar septa shows a vascular congestion and hemangiomatosis-like lesion. Notice the absence of acute lung injury, inflammation, and hyaline membrane formation. While originally described in the acute setting, this vascular congestion and hemangiomatosis-like lesion was identified in an explanted lung approximately 4 months after acute COVID-19 pneumonia.

Figure 10:

Histologic image (hematoxylin and eosin stain, 100× magnification) of pulmonary parenchyma shows organizing diffuse alveolar damage. There are residual alveolar spaces with marked increase in the interstitium by cellular fibroblastic proliferations. Some fibroblastic proliferations are also likely within alveoli. Type 2 pneumocyte hyperplasia is present. These findings were observed in an explanted lung approximately 6 months after acute COVID-19.

Figure 11:

Histologic image (hematoxylin and eosin stain, 100× magnification) shows diffuse pulmonary fibrosis in an explanted lung 6 months after acute COVID-19. There is deposition of paucicellular, eosinophilic material within the pulmonary interstitium. Some residual alveolar spaces are present but appear compressed. These findings have been previously described in explanted lungs and likely represent the fibrotic phase of diffuse alveolar damage.

Figure 12:

Histologic image (hematoxylin and eosin stain, 100× magnification) shows numerous fungal hyphae with acute angle branching and septations. These fungal hyphae are favored to represent Aspergillus, but no culture data were available. The fungi are seen in a background of marked neutrophilia, consistent with a necrotizing abscess.