The typical chest computed tomography (CT) findings of the novel coronavirus disease 2019 (COVID-19) appear as multiple patchy, ground-glass opacities that progress to or co-exist with bilateral consolidations in multiple lobes and with peripheral distribution[1–3]; however, the cystic features of COVID-19 on CT have not yet been reported in the literature. Here, we report the chest CT findings of cystic lesions in 2 patients confirmed to have COVID-19 pneumonia. Of note, written informed consent was obtained from both patients to publish this case report.
2 Case report
2.1 Case 1
A 38-year-old man diagnosed with severe COVID-19-related pneumonia (6 days) was admitted to the intensive care unit. The primary CT findings showed bilateral, patchy, ground-glass opacities with co-existing consolidations (Fig. 1A). The patient presented with shortness of breath, chest pain, 92% percutaneous oxygen saturation, and 26 breaths/minute; the patient was thus given 5 L/minute of oxygen by mask. However, 26 days later, follow-up CT findings showed multiple cysts in the ground-glass opacities (bilaterally) and the development of a ∼20% left pneumothorax. The cysts had a smooth inner wall and the maximum diameter of these cysts was ∼5 cm (Fig. 1B). At this time, real-time fluorescent polymerase chain reaction of the patient's sputum was negative for COVID-19 nucleic acid. The patient continued to be given 4 L/minute of oxygen by mask, as well as an antitussive, phlegm-dispelling treatment. The third CT scan, which was performed 5 days after the second CT scan, showed that the left pneumothorax and 1 small cyst on the left pulmonary margin had disappeared; the remaining cysts were slightly reduced in size (Fig. 1C). The patient was discharged from the hospital 21 days after the third CT scan.
2.2 Case 2
A 35-year-old man diagnosed with severe COVID-19 pneumonia (9 days) was admitted to the intensive care unit. The primary CT findings showed bilateral, patchy, ground-glass opacities and consolidations (Fig. 2A and B). The patient developed acute respiratory distress syndrome (ARDS) and type I respiratory failure; as such, the patient was given assisted respiration via a noninvasive ventilator (the inspiratory positive airway pressure ranged from 20 to 26 cm H2O; the expiratory positive airway pressure ranged from 5 to 10 cm H2O), as well as anti-infective, antivirus treatment. Forty days later, the CT scan findings showed bilateral, patchy consolidations, and multiple cystic lesions (bilaterally) with peripheral distribution (Fig. 2C and D). At present, real-time fluorescent polymerase chain reaction of the patient's sputum was negative for COVID-19 nucleic acid. To treat the patient's paroxysmal cough, which featured a little white mucus, as well as to address the patient's 97% percutaneous oxygen saturation with 19 breaths/minute, the patient's antitussive, phlegm-dispelling treatment was continued. Two days later, the multiple cystic lesions were slightly reduced in size on follow-up CT (Fig. 2E and F). At the time this paper was submitted for publication, the patient had been transferred to the rehabilitation department.
To date, the papers published on COVID-19 have not discussed the presence of cystic lesions in association with this disease. In both of our cases, the pulmonary cystic lesions of COVID-19 were found on CT.
The pulmonary cystic lesions and pneumothorax that were found may have been complications associated with mechanical ventilation.[4,5] The incidence of barotrauma in patients with ARDS following ventilation therapy was 6.5%. Most ventilation-associated cysts were small (<1 cm in diameter) and featured a thick wall with no appreciable internal structure, and were found in a subpleural location. However, some of the literature reported that ARDS might independently result in cyst formation.[7,8] The pulmonary cysts were observed in severe acute respiratory syndrome patients who received only short-term, low-pressure, and volume ventilation or received no mechanical ventilation at all. The reasons for this might include the development of ischemic parenchymal damage, lung fibrosis, low lung compliance, and inflammatory exudate in the airway.[7–9]
The pulmonary cysts and pneumothorax that were observed in both of our cases occurred more than 30 days after symptom onset; both patients were in the intermediate and late stages of ARDS, which is when fibrous processes begin to appear. Case 1 did not receive mechanical ventilation therapy; therefore, we speculate that ischemic parenchymal damage, lung fibrosis, and low lung compliance may have led to the formation of cysts and the development of a pneumothorax. Case 2 received a noninvasive ventilator; thus, the application of the ventilator may have constituted an additional reason for the formation of cysts and the development of a pneumothorax.
Recent histological examinations reported bilateral diffuse alveolar damage with cellular fibromyxoid exudates in COVID-19. Pulmonary cystic lesions may form in response to cellular fibromyxoid exudates, which form a valve in the bronchus. Since these lesions cause emphysema and bullae, phlegm-dispelling treatment options may have been more appropriate and effective for both of our cases.
In conclusion, COVID-19 may independently result in pulmonary cyst formation and the development of a pneumothorax; however, the use of a ventilator to manage the symptoms of this disease may be another reason underlying the formation of these lesions in patients affected by this virus.
We thank our colleague, Xinyi Wang, for helpful discussions in article revision. English-language editing of this manuscript was provided by Journal Prep Services.
Data curation: Kefu Liu, Yuanying Zeng, Ping Xie, Xun Ye, Guidong Xu, Jian Liu, Jinxian Qian.
Funding acquisition: Kefu Liu.
Writing – original draft: Ping Xie, Yuanying Zeng, Hao Wang.
Writing – review & editing: Kefu Liu, Jinxian Qian.
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