Spontaneous Pneumomediastinum in a Patient with Coronavirus Disease 2019 Pneumonia and the Possible Underlying Mechanism

Dear Editor,

We read the article by Sun et al. (1) in the Korean Journal of Radiology with great interest concerning the computed tomography (CT) findings of coronavirus disease 2019 (COVID-19). The report demonstrated that mediastinal emphysema, giant bulla, and pneumothorax developed as complications of COVID-19 pneumonia during the course of the disease.

Spontaneous pneumomediastinum seems to be rare in COVID-19. Here, we share our opinions on the possible mechanism underlying pneumomediastinum in COVID-19 pneumonia. Further, we report a case of spontaneous pneumomediastinum in a COVID-19 patient (Fig. 1) that was found to resolve on follow-up CT images at our hospital. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, and other coronaviruses that cause SARS and Middle East respiratory syndrome might have similar characteristics as they belong to the same family Coronaviridae. Spontaneous pneumomediastinum was reported in patients with SARS in 2003 (2). A study showed that a substantial proportion (12%) of patients with SARS could develop spontaneous pneumomediastinum unrelated to the use of positive end-expiratory pressure ventilation (2). In SARS, spontaneous pneumomediastinum occurs most frequently when the ground-glass opacities (GGOs) and consolidations in the lungs begin to resolve (3). In this situation, peribronchiolar abscess formation probably leads to interstitial pulmonary emphysema, which tracks back along the bronchovascular sheath and reaches the mediastinum (3). Subsequently, chest CT shows spontaneous pneumomediastinum (3). We believe that the mechanism underlying pneumomediastinum in patients with COVID-19 pneumonia is similar to that in patients with SARS because the viruses in the same Coronaviridae family may have similar pathogeneses and imaging features. At our hospital, one (7.14%) out of 14 patients with COVID-19 pneumonia developed spontaneous pneumomediastinum. The patient was a 64-year-old man complaining of fever and fatigue for 7 days. He had a history of recent travel to an area with the COVID-19 epidemic. Chest CT performed 17 days after the onset of symptoms showed progressive resolution of the patient's pneumonic lesions and the presence of spontaneous pneumomediastinum in the anterior mediastinum (Fig. 1A), which had been absent on CT performed at the time of the initial diagnosis (not presented). Follow-up CT performed 24 days after the onset of symptoms revealed resolution of the previously seen anterior pneumomediastinum (Fig. 1B).

Fig. 1
64-year-old man with coronavirus disease 2019.
A. Chest CT scan obtained 17 days after onset of symptoms shows GGOs (black arrowhead) and consolidations (white arrow) with spontaneous pneumomediastinum (black arrow) in anterior mediastinum. B. Follow-up CT scan obtained 24 days after onset of symptoms shows resolution of anterior pneumomediastinum (not shown), reduced GGOs, increased consolidations or GGOs mixed with consolidations (white arrow), and reticular opacities (white arrowhead) in lung parenchyma. CT = computed tomography, GGOs = ground-glass opacities

• Click for larger image
• Download as PowerPoint slide

Some typical CT features are observed in the patients with COVID-19 pneumonia. GGOs and consolidation are distributed in the peripheral bronchovascular or subpleural areas in the lower lobes, particularly in the right lower lobe, in the early stage. In the advanced or severe stages, GGOs decrease, and GGOs mixed with consolidation or consolidation increase. Fibrosis can be detected as lung lesions dissipate. This case as well as the previously reported cases might indicate that spontaneous pneumomediastinum on CT may be discovered in the late stages when GGOs and GGOs mixed with consolidations begin to resolve.