Delayed symptomatic cavity formation in COVID-19 pneumonia

A 20-year-old male with a history of asthma presented with cough and fever. He was diagnosed with COVID-19 pneumonia (positive throat PCR swab) and pulmonary emboli. He was treated with Apixaban, Piperacillin-Tazobactam and Continuous Positive Airway Pressure (CPAP). He represented one month later with pleuritic chest pain and exertional breathlessness.

His initial Chest X-ray (CXR) showed bilateral lower zone consolidation (Figure 1). A CT Pulmonary Angiogram (CTPA) revealed features of severe COVID-19 pneumonia; multifocal ground-glass opacities, dense consolidation in the right middle lobe and lingula, small bilateral subsegmental pulmonary emboli and a small left pleural effusion (Figure 2a). There was no dilatation of the peripheral vessels travelling towards or within the areas of ground glass shadowing [1]. 

The CTPA on readmission showed resolution of pulmonary emboli and left pleural effusion. New multiple, bilateral, peripheral, thick smooth walled cavities were present (Figure 2b and c). The largest cavity, in the right lower lobe, measured 11cm and contained an air-fluid level (Figure 3). A new small right pleural effusion and moderately enlarged mediastinal lymph nodes (>1cm) were present, which is suggestive of severe COVID-19 infection [2, 3] or superadded infection.

Background:

Delayed cavitation has been rarely described as a pulmonary manifestation of COVID-19 [4-7].

Typical acute features of COVID-19 pneumonia include ground-glass opacities, interstitial thickening with ‘crazy-paving’, ‘halo and reverse-halo signs’ and consolidation with air bronchograms [8].

Clinical Perspective:

Atypical features of COVID-19 raise concern for other infection or additional diagnoses [9,10]. Bacterial and Fungal infection should be excluded, as well as cavity-forming organisms [4]. Fungal (Beta-D Glucan and Aspergillus serology), atypical bacterial and vasculitic screens were negative in our patient.

There is no consensus on how post COVID-19 cavities should be managed with very few reports of such a complication. Of these, most have been managed conservatively with only one case reporting excision of infected pneumatoceles [4].

Imaging Perspective:

Very large post COVID-19 cavities have not been previously reported such as in our case.

Mechanical ventilation, ischaemic parenchymal damage [7] and post-consolidation alveolar walls disruption with pneumatocele formation [8] were proposed as mechanisms for cystic lesions and pneumothorax.

Pneumatoceles are thin-walled parenchymal cysts that can complicate severe pneumonia. Histology of pneumatoceles shows inflammation and necrosis of airway walls with formation of direct communication between the bronchovascular interstitium and the pulmonary parenchyma [11]. Interval imaging can differentiate pneumatoceles from lung abscess, due to their characteristics of rapid change in appearance, size and location [12]. Pneumatoceles resolve spontaneously.

High incidence of pulmonary emboli (PE), up to 30%, has been reported in patients with COVID-19 [13].  A COVID-19 PE phenotype is suggested, as clots commonly occur in peripheral vessels, possibly due to thromboembolic disease and in situ immunothrombosis [14]. Cavitation, due to aseptic liquefaction or secondary infection [15], can complicate pulmonary infarction in 2.7-7% of cases [16] and was reported during the 2003 SARS pandemic [17].

The largest cavity in our patient, contained an air-fluid level which raised the suspicion of a  broncho-pleural fistula; a communication between the pleural space and the bronchial tree.  A definite airway - cavity communication was not identified after careful review of CT reconstructions in all planes, however this does not necessarily rule out a broncho-pleural fistula

Outcome:

Percutaneous drainage of the largest, fluid-filled cavity was considered, but not performed on MDT (Multi-Disciplinary Team) consensus, as the patient’s modest symptoms did not warrant the risk of introducing pleural infection and creating a bronchopleural fistula. 

The patient was treated conservatively and monitored with serial CXRs for six weeks (Figures 4 and 5). These showed reduction in size of the cavities with resolution of the air-fluid level.

Teaching points:

• Delayed cavitation is a rare, symptomatic feature of Covid-19 pneumonia.
• Exclusion of additional pathologies and close clinic-radiological cooperation should guide treatment.
• In well individuals, post Covid-19 cavitation may be successfully managed conservatively.  
• Lymphadenopathy may be a predictor of worse outcome in severe COVID-19 pneumonia

Written informed patient consent for publication has been obtained.