Atypical presentation of a fish bone foreign body: A case report and review of the literature

Introduction: Fish bone Foreign Body (FFB) accidental ingestion is a most common presenting complaint for patients attending the emergency department. It is more frequently lodged within the oropharynx and the oesophagus. However, fi sh bone impacting in the respiratory system is extremely rare; accounting for 14% of reported cases, with approximately few cases reported in the literature involved the lower airway.


Introduction
Foreign body ingestion is a common presentation in the Emergency Room (ER). Fish Bone Foreign Body (FFB) ingestion is the most common cause of accidental food-associated foreign body ingestion (84%) [1] in the Mediterranean and Asian populations, especially in the coastal areas [2]. The majority of these bones pass through the gastrointestinal tract without symptoms or complications, and <5% of the patients with accidentally ingested fi sh bones develop complications [2,3].
Here, we report one of the fi rst cases of an atypical location of an ingested fi sh bone, impacting the lung parenchyma, which was visualized by a computerized tomography (CT) scan. This case report highlights the importance of vigilant and thorough history taking and a physical examination not only by emergency physicians, but also specialists including, gastroenterologists, cardiothoracic surgeons and radiologists.

Case report
A 27-year-old man with an unremarkable medical history presented to the Respiratory Zone in the Emergency Department with a 5-day history of palpitation, right pleuritic chest pain, shortness of breath, and no documented fever. The swab for COVID-19 was negative, 1 day before the presentation.
As his swab was negative and his clinical presentation was not suggestive for COVID-19, he was transferred to the Emergency Department for further investigations. On examination, he had stable vitals, although his heart rate was 136 beats/min. A chest examination revealed decreased air entry on the right side and the electrocardiogram (ECG) showed sinus tachycardia.
An initial chest X-ray was performed in the supine position ( Figure 1) and the main concern at that time was to exclude the presence of a COVID-19-related chest infection as his symptoms were suggestive of chest problems. Therefore, the ingested foreign body diagnosis was initially missed. The patient was seen by the Emergency Department specialist and discharged from the Respiratory Zone to the Emergency Department as the COVID-19 swab was negative.
The ECG showed Q3 T3 changes and he was tachypneic. The CT pulmonary angiography for pulmonary embolism was negative ( Figure 2). However, there was an incidental fi nding in the right lower lung; there was a 2.8-cm, long hyperdense linear structure of osseous density with adjacent tiny foci of similar density and a surrounding consolidation suggestive of a foreign body, likely to be a fi sh bone (Figures 3a,b-5a,b). The patient was referred for an emergency bronchoscopy and an evaluation by the thoracic surgeon. The opinion was that the foreign body was not the cause of the patient's symptoms as it was distal within the lung parenchyma; therefore, there was no need for urgent surgical intervention and there should be a 1-month outpatient clinic follow-up. He was discharged with antibiotics (for 10 days duration) for a chest infection and an appointment for the follow-up in the outpatient clinic. The management plan was discussed with him and his perspectives were taken in consideration. He was followed up at 1 month Figure 1: Initial chest X-ray showed poor inspiratory effort and no air space opacity. A linear hyperdensity is noted in the right lower lung, which was initially missed.   and 2 months, he was doing well and his initial complaints that he presented at the emergency department were resolved with no new complaints. The chest X-ray was repeated and revealed an unchanged appearance of the linear hyperdense foreign body in the right lower lung ( Figure 6). All the ethical protocols were followed, and the patient gave informed consent for publication of this case report. The patient's information was de-identifi ed.

Discussion
Accidental FFB ingestion is a common ER presentation in geographical areas where regular consumption of unfi lleted fi sh is popular. Although the age distribution of FFB ingestion varies, the highest prevalence is in young children (aged 1-11 years) and middle-aged adults (aged 30-59 years old) [4,5]. In adults, the majority of FFB are impacted in the oropharynx and the esophagus (about 86%) [6], and are largely expelled from the gastrointestinal tract without intervention. However, 10-20% of cases need emergency endoscopic removal [1]. Although an FFB rarely migrates to the lower respiratory system [1], tracheobronchial foreign body aspiration has been reported in 14% of FFB cases [4]. Typically, the lower respiratory system involvement occurs in adults with underlying neurological or medical conditions [7]. In the present case report, however, we reported an atypical presentation of FFB aspiration in a healthy man aged 27 years. Due to the nonspecifi c clinical presentation, adult lower airway FFB aspiration is easily misdiagnosed.
Evidence about direct presentation of lower airway FFB impaction is limited. The majority of the reported literature showed the involvement of the lungs secondary to a longstanding FFB impaction and complete esophageal wall penetration, which led to a lung abscess, recurrent pneumonia, tracheoesophageal fi stula, empyema, and pneumothorax [4]. Additionally, FFB impaction has caused lung collapse and obstructive pneumonia [1]. These severe complications are associated with poor prognosis; and depend on the presence of many risk factors. Lower airway FFB is uncommon in adults and usually obscure or indirect. In fact, eating habits can infl uence FFB impaction in the lower airway. Habits vary between countries and have been found to be different in Chinese adults compared to Western adults [8]. Worldwide, fi sh fi n has been thought to be inedible. However, it is popular in China where Chines like the taste of the fl esh surrounding the fi n [4,8]. Other risk factors include the bone type and length of the bone (>3 cm) [4]. A long time lapse after FFB ingestion can predispose the patient to lower airway FFB impaction. An 80-year-old Chinese woman had an aspirated fi sh fi n that migrated into the lower airway and remained undiagnosed for 3 years [9]. If left untreated, this FFB in Chinese woman could have caused several lung complications. A lung abscess, although rarely induced by an FFB, was reported in a middleaged woman who had a continuous dry cough and fever [10].
Our patient presented with atypical symptoms of an FFB ingestion during the COVID-19 pandemic. His respiratory symptoms were typical of a pulmonary embolism. Based on the patient's presenting symptoms, a primary imaging modality is a simple chest X-ray, which was followed by a CT pulmonary angiography to rule out the presence of a pulmonary embolism. Although simple radiography has low sensitivity, if severe complications or perforations are present, ordering a CT scan for every suspected FFB is not recommended [11]. CT scans are expensive and have high false-negative rates; they expose the patients to unnecessary high radiation [12]. Imaging patients with ambiguous or atypical symptoms, including geriatric [8,13,14], and young healthy patients [13] has little diagnostic value [15]. However, the benefi ts and risks of a CT scan are highly individualized. Some severe cases with a clear history of FFB ingestion do mandate a CT scan as FFB ingestion is usually diffi cult to identify on a plain chest X-ray [16]. For example, an FFB ingestion was revealed when a non-contrast CT scan was performed to diagnose a patient with severe retrosternal chest pain with a clear history of accidental FFB ingestion 5 days before the symptoms. The scan revealed a bilateral cystic bronchiectasis with a 20-mm-long and 2-mm-thick hyperdense fi sh bone. Almost 95% of the FFB penetrate the posterior wall of the esophagus. Therefore, a chest CT scan with contrast revealed the complication of the FFB, which was a bronchial artery pseudoaneurysm developing from a hypertrophied right bronchial artery that was in close contact with the fi sh bone [2].