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Migratory fishbones in the pharynx: A report of two cases

Abstract The possibility of fishbone migration into the surrounding tissues, especially in cases where it cannot be identified on routine inspection. Early diagnosis of migratory fishbone and therapeutic management are essential for optimal patient survival.


| INTRODUCTION
Fishbones migrated into surrounding tissues are relatively unusual. We present two cases of patients' migratory fishbones into the retropharyngeal space and hypopharynx. All fishbones were removed without complications. Early diagnosis of migratory fishbone and therapeutic management are essential for optimal patient survival.
Foreign bodies (eg, fishbones) stuck in the pharynx are the most common emergency cases in otorhinolaryngology practice. Sharp and pointed fishbones may damage the mucosa. In a majority of cases, however, these can be easily removed. In rare cases, fishbones can migrate to the different parts of the body causing deep neck space infection, 1 large blood vessel rupture, 2 and gastrointestinal perforation 3 if not promptly managed.
Here, we describe two cases of patients' migratory fishbones into the retropharyngeal space and hypopharynx. We discuss our experience in treating these cases using a specific approach for each patient.

| Case 1: migratory fishbone in the retropharyngeal space
A 62-year-old man presented with sudden onset pharyngeal pain after eating fish at a local hospital. Fiber-optic laryngoscopy showed no abnormalities. Computed tomography (CT) revealed a foreign body lying transversely at the right piriform fossa. Painless gastroscopy was performed to remove the foreign body; however, no foreign bodies were detected. During gastroscopy, he presented with laryngeal edema, which required tracheal intubation.
Four days after admission, he was referred to our hospital for management. Cervical CT showed a foreign body in the right retropharyngeal space between the cervical vertebrae 1 and 2 ( Figure 1A,B). Subsequently, he underwent surgical exploration of the retropharyngeal space under general anesthesia. During surgery, the foreign body could not be detected in the plane of the second cervical vertebra. An extended longitudinal incision was performed to find the fishbone in the surrounding tissues. Fortunately, a fishbone was found in the plane of the third cervical vertebra. A 1-week follow-up revealed the absence of pain and foreign body sensation.

| Case 2: migratory fishbone in the hypopharynx
A 52-year-old man was admitted to our department for throat pain, foreign body sensation, dysphagia, and mild sialorrhea for 3 days after eating fish. Cervical CT confirmed the presence of a linear radiopaque structure in the left laryngopharynx (Figure 2A,B). Flexible fiber-optic laryngoscopy did not identify a foreign body in the area but this revealed the absence of mucosal lesions ( Figure 2C). To further ascertain the presence of a foreign body in the hypopharynx, a gastroscopy was performed showing a fishbone in the left piriform fossa ( Figure 2D). The fishbone pierced from the left piriform fossa into the posterior pharyngeal wall. The object was extracted using forceps. The patient immediately felt comfortable.

| DISCUSSION
Here, we describe two cases of migratory fishbones in the pharynx that were not observable via flexible fiber-optic laryngoscopy. We used a specific treatment for each patient. Fortunately, all patients had favorable outcomes.
Patients suspected of having fishbone impaction usually undergo physical and laryngoscopic examinations. A fishbone at the base of the tongue or hypopharynx usually requires flexible fiber-optic laryngoscopy for observation. However, it is difficult to determine the precise localization of fishbones in cases with an endoscopically undetectable fishbone. Sharp fishbones are more prone to cause mucosal damage. Moreover, muscle contractions after entering the pharynx may contribute to migration. 4 Migratory fishbones are associated with an increased incidence of complications. Therefore, it is important to establish this diagnosis early and accurately. CT is considered the most sensitive (sensitivity =100%) modality for detecting ingested fishbones in soft tissues. 5 Therefore, CT is recommended when suspecting the migration of ingested foreign bodies, as demonstrated in the present cases.
The retropharyngeal space consists of loose soft tissue between the buccopharyngeal fascia and the prevertebral fascia. Owing to this structure, fishbones can migrate freely into the retropharyngeal space. This was consistent with our observations on the first case. During the operation, it is difficult to identify the location of the fishbone in the retropharyngeal space. We suggest the use of CT to approximate the position of the fishbone, followed by an extended longitudinal incision to identify its exact location in the surrounding tissues.
The incidence of foreign bodies in the hypopharynx is common. However, complete visualization of the foreign body is usually limited by the anatomically closed hypopharynx in its resting state. Modified Killian's method can be applied to remove an endoscopically invisible fishbone. 5 Unfortunately, the second patient had severe sore throat symptoms upon head flexion and rotation. In this case, we removed the fishbone through gastroscopy, which fully exposed the hypopharynx.