Discussion
Two cases we described are migratory fish bones in the pharynx. They were hidden in the flexible fiberoptic laryngoscopy. We adopted specific treatment for each patient. Fortunately, every patient had a favorable outcome.
Patients suspected of fish bone impaction usually undergo physical and laryngoscopic examination. A fish bone in the base of tongue or hypopharynx usually requires flexible fiberoptic laryngoscopy for observation. However, it is difficult to determine the precise localisation of fish bone in cases with an endoscopically invisible fish bone. Sharp fish bone is prone to damage to the mucosa, and muscle contractions after entering into the pharynx may contribute to the migration4. Migratory fish bone is associated with an increased incidence of complications. Therefore, it is important to make a diagnosis correctly. CT scan is considered as the most sensitive modality for detecting ingested fish bones due to it has a sensitivity of 100% in the soft tissues5. Therefore, CT is recommended in cases of suspected migration of ingested foreign bodies into surrounding tissues, as demonstrated in the present cases.
The retropharyngeal space consists of the loose soft tissue between the buccopharyngeal fascia and the prevertebral fascia. Due to the structure of the retropharyngeal space, we surmised that fish bone can migrate freely in the retropharyngeal space. Indeed, we found that fish bone entered the retropharyngeal space can swam away in the first case. During the operation, it is difficult to identify the location of fish bone in the retropharyngeal space. We suggest that locating the approximate position of the fish bone by CT, in addition, surgeons should prolong the longitudinal incision to find it in the surrounding tissues.
The incidence of foreign bodies in the hypopharynx is not uncommon. However, complete visualization of the foreign body in the hypopharynx is usually difficult because most of the hypopharynx is anatomically closed in the resting state. Modified Killian’s method can be applied to remove of an endoscopically invisible fish bone5. Unfortunately, the second case had severe sore throat symptoms when he bowed and turned head. We removed the fish bone through gastroscopy. During the course of gastroscopy, the hypopharynx was fully exposed. This suggests gastroscopy may be a good alternative method for visualization and removal of fish bones in such cases.