Fish Bone Descending in the Mediastinum

Abstract

Ingested sharp foreign bodies rarely migrate extraluminally into adjacent organs such as the pharynx, lungs, and liver. Herein, we report a case of fish bone ingestion where the foreign body followed a unique migration trajectory. Computed tomography revealed a fish bone extraluminally located in the aortopulmonary space in the left mediastinum and peri-esophageal pneumomediastinum. Endoscopic examination indicated no injury to the esophageal mucosa but showed mucosal lacerations in the left hypopharynx. Accordingly, we reasoned that the fish bone penetrated the laryngopharynx and then descended in the mediastinum.

Introduction

Foreign body (FB) ingestion is a commonly encountered problem in otolaryngology and gastroenterology. Digestive tract perforations caused by FBs account for approximately 1% of FB ingestions, requiring surgical intervention for associated mediastinitis or great vessel fistulas. Surprisingly, penetrating FBs can migrate extraluminally into adjacent organs, including the pharynx, mediastinum, lungs, and liver. It is essential to understand the migration trajectory to provide patients with effective curative care in such cases.

Case Report

A 23-year-old male with no past medical history presented to the emergency department with a “stabbing” chest pain. He reported the pain started when he ingested grilled fish in the morning. His vital signs were notable for tachycardia (135 beats per minute) and elevated body temperature (38.6°C), while blood pressure was within a normal range (127/58 mmHg). Chest computed tomography revealed a thin, approximately 1-cm long FB with bone density beneath the aortic arch and peri-esophageal pneumomediastinum extending from the cervix to the middle thorax (Figs. 1A and 1B). He was diagnosed with pneumomediastinum secondary to migrating fish bone. Upper gastrointestinal endoscopy revealed a blood clot and mucosal laceration in the left pyriform fossa (Figs. 1C and 1D) but indicated no signs of injury on the esophageal lumen. We decided to surgically explore the mediastinum because of the potential progression of mediastinitis and possible FB’s involvement with adjacent vessels. The left-side thoracoscopic examination revealed an edematous change in the mediastinal tissue; thus, the superior to posterior mediastinal pleura was opened. A thin, stick-shaped FB was identified in the left mediastinum, located anteriorly to the left vagal nerve, posteriorly to the ductus arteriosus, and inferiorly to the aortic arch (Fig. 2A). The FB had no contact with the esophageal wall and was not involved with adjacent vessels. A drainage tube was placed in the opened mediastinum via the pleural space. Postoperative microscopic examination of the removed FB (Fig. 2B) showed a reticulated, calcified structure (Fig. 2C) consistent with bone tissue. The postoperative course was uneventful. Swallowing video fluorography performed on postoperative day (POD) 2 revealed no communication with the mediastinum; thus, the patient resumed regular diet on POD 3. The pleuromediastinal drainage tube was removed on POD 5, and then the patient was discharged on POD 6. Ampicillin–sulbactam was administered intravenously throughout the hospital stay and orally for 7 days after the hospital discharge.

Fig. 1. (A and B) Coronal view (A) and axial view (B) of CT showing an FB (arrow) beneath the aortic arch and periesophageal pneumomediastinum (arrowheads). Asterisk, trachea; e, esophagus. (C and D) The upper gastrointestinal endoscopy showed blood clots (C, arrows) and a mucosal laceration (D, arrow) in the left pyriform fossa. Asterisk, tracheal tube. CT: computed tomography; FB: foreign body.

Fig. 2. (A) The FB (arrow) grasped by Maryland forceps during thoracoscopic surgery. Asterisk, the aortic arch; arrowheads, the left vagal nerve encircled by a blue tape. (B) The removed FB. Scale bar, 5 mm. (C) Pathological image of the FB (H&E stain). FB: foreign body; H&E: hematoxylin and eosin.

Discussion

Approximately 1% of patients who have a FB lodged in the digestive lumen are reported to develop perforation of the digestive tract.¹⁾ Less frequently, FBs can migrate into adjacent organs or compartments, such as the lungs and liver.^2,3) Once perforated or additionally migrated, prompt surgical intervention should be considered to prevent otherwise life-threatening conditions, including mediastinitis or abscess in affected organs and inflammation-associated great vessel fistula.^3–5) Our patient had a mild mediastinal inflammation on admission. As an inadequate response to conservative management could lead to more complicated conditions involving adjacent great vessels or the vagal nerve, we performed the pleuromediastinal drainage and FB removal in an early inflammatory phase.

In our case, the fish bone was identified in the left mediastinum with no apparent contact with the esophageal wall. Furthermore, endoscopic examination revealed laceration in the left hypopharynx but no injury to the esophageal mucosa. Accordingly, we concluded that the fish bone entered the cervical mediastinum from the laryngopharynx and then descended via the intra-mediastinal route reaching the aortopulmonary space. The supposed perforation site (Figs. 1C and 1D) is surrounded by the inferior constrictor muscle of the pharynx and the cricopharyngeus muscle, which form the upper esophageal sphincter. We guess that the FB was compressed to penetrate the hypopharynx wall by the swallowing movement and the associated dynamic change in the intraluminal pressure. On the other hand, the connective tissue surrounding the mediastinal structures is loose, easily separated by air or fluid, and exemplified by cervicothoracic emphysema and descending mediastinitis.⁶⁾ The fish bone of our patient presumably moved through “the aerated mediastinal passage” formed by a relatively weak force trigger such as cough. FBs can follow unusual migratory trajectories. This case is a good example showing that extraluminal FBs require the examination of the digestive tract for potential distant perforation sites.

Conclusion

We reported an unusual case of the ingested fish bone that descended in the mediastinum.

Disclosure Statement

The authors have no conflicts of interest to declare.