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Unrecognized tooth aspiration mimicking a hilar lesion in a patient with COVID-19 pneumonia

Pang-Yen Chen1,2,3,4,5orcid, Chien-Wei Chen6,7orcid, Yu-Jang Su1,2,3,4,8,*orcid
Ewha Med J 2026;49(3):e24. Published online: July 14, 2026

1Department of Emergency Medicine, MacKay Memorial Hospital, Taipei, Taiwan

2Department of Nursing, Yuanpei University of Medical Technology, Hsinchu, Taiwan

3MacKay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan

4Department of Medicine, MacKay Medical University, New Taipei City, Taiwan

5Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu, Taiwan

6Department of Medical Imaging and Intervention, Linkou Chang Gung Memorial Hospital, Linkou, Taiwan

7College of Medicine, Chang Gung University, Taoyuan, Taiwan

8Toxicology Division, Emergency Department, MacKay Memorial Hospital, Taipei, Taiwan

*Corresponding email: yjsu.5885@mmh.org.tw
• Received: April 24, 2026   • Revised: June 10, 2026   • Accepted: July 3, 2026

© 2026 Ewha Womans University College of Medicine and Ewha Medical Research Institute

This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by-nc/4.0/), which permits noncommerical use, distribution, and reproduction in any medium, provided the original work is properly cited.

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A 77-year-old nursing home resident with hypertension and chronic obstructive pulmonary disease presented to the emergency department with fever and dyspnea of 2 days’ duration. No choking episode had been witnessed, and SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) testing was positive. On examination, he was tachypneic, with a respiratory rate of 32 breaths/min, an oxygen saturation of 88% on room air, and markedly diminished breath sounds over the left hemithorax.
Laboratory tests showed a white blood cell count of 6,900/μL with 15% band forms, a C-reactive protein level of 163 mg/L, and a procalcitonin level of 0.05 ng/mL. Arterial blood gas analysis while the patient was receiving 10 L/min of oxygen showed alkalemia, with a pH of 7.55, PaCO2 of 43 mm Hg, and HCO3⁻ of 36.5 mmol/L, as well as hypoxemia, with a PaO2 of 71 mm Hg. A portable chest radiograph showed bilateral infiltrates and pleural effusions; it also showed hyperinflation of the left lung (Fig. 1). This unilateral hyperinflation was later attributed to a check-valve mechanism caused by the aspirated tooth in the left main bronchus: airflow entered the distal airways through the partially obstructed bronchus during inspiration, but expiratory airflow was impeded, causing air trapping. This radiographic pattern is a characteristic clue to foreign body aspiration. Thoracentesis yielded a sterile, lymphocyte-predominant transudative effusion, consistent with viral pleuritis and volume overload rather than empyema.
Despite treatment for coronavirus disease 2019 (COVID-19), severe hypoxemia and left-sided hypoventilation persisted. On hospital day 23, re-evaluation of the admission radiograph revealed a subtle radiopaque structure superimposed on the left hilum (Fig. 1, arrow) that had initially been dismissed as benign calcification. Subsequent chest computed tomography showed an aspirated tooth in the left main bronchus, causing complete obstruction and atelectasis (Fig. 2A). Lung-window images demonstrated distal air trapping compatible with a check-valve mechanism caused by the aspirated tooth (Fig. 2B). Flexible bronchoscopy revealed the tooth embedded in granulation tissue (Fig. 2C). Removal briefly improved oxygenation, but the clinical course was complicated by postobstructive pneumonia, methicillin-resistant Staphylococcus aureus bacteremia, and multidrug-resistant Acinetobacter baumannii infection. The patient died on hospital day 106.
The requirement for informed consent was waived by the Institutional Review Board (IRB No. 202501221B0).
Foreign body aspiration in adults is frequently unwitnessed and may be diagnosed without a history of choking, particularly in older adults with dentures or diminished airway reflexes [1]. In this case, the aspirated tooth mimicked a calcified hilar lesion: projectional superimposition on a portable radiograph made the tooth resemble a calcified hilar lymph node.
The diagnostic delay was likely amplified by anchoring bias. After COVID-19 was confirmed, persistent hypoxemia was attributed to viral pneumonia, and the discordant bedside finding of asymmetric breath sounds was rationalized rather than investigated [2]. Persistent unilateral hypoventilation that is disproportionate to radiographic findings should prompt urgent evaluation for bronchial obstruction [3]. When clinical improvement stalls, deliberate repeat review of the initial imaging—with contrast and window settings adjusted to assess the central airways—may reveal a reversible cause before fatal complications develop.

Authors’ contribution

Conceptualization: PYC, YJS. Data curation: PYC, CWC. Investigation: PYC, CWC. Methodology: PYC. Validation: CWC. Project administration: YJS. Resources: CWC. Visualization: YJS. Supervision: YJS. Writing–original draft: PYC, CWC. Writing–review & editing: YJS.

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Data availability

Not applicable.

Acknowledgments

None.

Supplementary materials

None.

Fig. 1.
A portable anteroposterior chest radiograph showing bilateral infiltrates and pleural effusions. A radiopaque foreign body (arrow) is visible over the left hilum, with hyperinflation of the left lung due to distal air trapping.
emj-2026-01445f1.jpg
Fig. 2.
Coronal chest computed tomography shows a tooth (arrow) causing complete obstruction of the left main bronchus with distal lung collapse (A). Lung-window imaging demonstrates air trapping compatible with a check-valve mechanism caused by the aspirated tooth (arrow) (B). Flexible bronchoscopy shows the tooth embedded in granulation tissue during retrieval (C).
emj-2026-01445f2.jpg

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      Ewha Med J. 2026;49(3):e24  Published online July 14, 2026
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      Unrecognized tooth aspiration mimicking a hilar lesion in a patient with COVID-19 pneumonia
      Image Image
      Fig. 1. A portable anteroposterior chest radiograph showing bilateral infiltrates and pleural effusions. A radiopaque foreign body (arrow) is visible over the left hilum, with hyperinflation of the left lung due to distal air trapping.
      Fig. 2. Coronal chest computed tomography shows a tooth (arrow) causing complete obstruction of the left main bronchus with distal lung collapse (A). Lung-window imaging demonstrates air trapping compatible with a check-valve mechanism caused by the aspirated tooth (arrow) (B). Flexible bronchoscopy shows the tooth embedded in granulation tissue during retrieval (C).
      Unrecognized tooth aspiration mimicking a hilar lesion in a patient with COVID-19 pneumonia
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