Discussion
Here, we describe two cases of migratory fish bones in the pharynx that were not observable via flexible fiberoptic laryngoscopy. We used a specific treatment for each patient. Fortunately, all patients had favorable outcomes.
Patients suspected of having fish bone impaction usually undergo physical and laryngoscopic examinations. A fishbone at the base of the tongue or hypopharynx usually requires flexible fiberoptic laryngoscopy for observation. However, it is difficult to determine the precise localization of fish bones in cases with an endoscopically undetectable fishbone. Sharp fish bones are more prone to cause mucosal damage. Moreover, muscle contractions after entering the pharynx may contribute to migration4. Migratory fish bones 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 fish bones in soft tissues5. 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, fish bones 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 fish bone5. 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. This suggests that gastroscopy may be a good alternative for the visualization and removal of fish bones in such cases.