Bronchogenic cysts were the most common congenital cystic lesions of mediastinum, originated from the primitive foregut. The dorsal segment of the foregut formed the esophagus, while the ventral component formed the trachea[1, 2]. The mediastinal bronchogenic cyst was occurred when there was abnormal budding or branching of tracheobronchial tree within early stage of the gestation[1, 2, 10]. The most common location of bronchogenic cysts in mediastinum includes para-tracheal, sub-carina, hilar, para-esophagus and pericardium. Bronchogenic cysts were also reported in intra-pericardium, pre-sternal, supraclavicular spaces, sub-diaphragmatic, retro-peritoneal and skin[11–15].
For pare-esophageal bronchogenic cysts, the extramural pare-esophageal bronchogenic cyst was the most common type. They were always found anotomic closed to esophagus, with clearly borderline or with only a mind adhesion to gastrointestinal tract, which made the operative procedure difficult. Some cystic lesions tend to located in the wall of esophagus, but with lumen mucosa intact. This type of bronchogenic cysts had been recognized well as intramural esophageal bronchogenic cysts in the literatures[4, 5]. Even though the mass was completely embedded in the wall of esophagus, the pathology showing hyaline cartilage and respiratory epithelium in the wall of cystic lesions,which confirmed its bronchogenic origin[4, 5, 16].
In our case, here we emphasized a more rare type of para-esophageal bronchogenic cyst, in which the cystic lesion communicated to esophageal lumen through a prepared canal. To our knowledge, only five similar case of bronchogenic cyst had ever been reported, but the nation of the communication remained unclear[6–9]. The main controversial point was whether the communication existed congenitally or it was formed posteriorly. In 1978, Mindelzun R and his colleagues first reported a mediastinal bronchogenic cyst with esophageal communication. They believed that thought the surrounding inflammation made it impossible either surgically or pathologically to establish the exact etiology of the fistula formation. So whether this represents a post-inflammatory change or a congenital communication remained a matter of conjecture. In 1999 when Knezevic J and his colleagues present a case of a well prepared para-esophageal bronchogenic cyst connected with the esophageal lumen by a narrow canal composed of stratifed squamous epithelium. In this patient, the transition of the ciliated epithelium of the cyst into the stratifed squamous epithelium of the cystic canal serves to emphasize the close anatomic and embryologic relationship between esophagus and the bronchial cystic derivatives. Consider the context of their embryologic development from the foregut, as well as on a histologic basis, the presence of an esophageal communication was thought less remarkable. Our case was similar with Knezević J's report. We also found a well prepared cyst connected to esophageal lumen through a canal, on which the inner face of the canal was covered by intact sequential mucosa. This rare type might be classified as lumen-communicated pare-esophageal bronchogenic cysts, which should not be confused with fistula between a mediastinal cysts and esophagus due to inflammatory invasion. The latter are often characterised by ulcerative change under endoscopy with mucosa destroy, confirmed by Olivier N. Pages and his colleague, In their report, an ulcero-necrotic esophageal wall over a 3 cm2 zone was found and a fistula of the bronchogenic cyst into the esophagus was revealed in video-assisted thoracoscopic surgery in emergency revealed. Instead of an intact inner face of canal confirmed in Knezević J's study and our case research. In our opinion, a lumen-communicated pare-esophageal cyst should include some teatures. First, a well prepared pare-esophageal cystic lesion communicated to esophageal lumen. Second, the communication happened through complete canal. Third, the inner face of the canal was covered by intact sequential mucosa characterized by respiratory epithelium to enteric lining. The fourth, there was no evidence of fistula, and there was a non-ulcerative appearance under endoscopy, which are similar with esophageal diverticulum. Although the incidence of communication between the esophagus and the bronchial cystic derivatives has not been established, from the 6 cases include ours reported, we should considered the existence of this rare type of bronchogenic cysts.
The clinical symptoms of patients with bronchogenic cysts were varied according to the lesions' size, location and communication. For the Pare-esophageal cysts, the patient more likely present symptoms of dysphagia and chest pain due to compression and pleural irritation[1, 3, 4]. But for the lumen-communicated pare-esophageal cyst, the symptoms may also associated with the penetration of liquid and air through the canal from the esophagus into the cyst. This can explain why our patient present with an irreversible dysphagia and chest pain in his past history. However, Infection was no found in our case.
For a pare-esophageal cyst, an accurate pre-operative diagnosis was difficult. Classic imaging features clould only infer the possible of lesion. Although accurate diagnosis must be provided by postoperative pathology, and per-operative differentiation should include other cystic lesions around esophagus, such as esophageal duplication cyst, esophageal malioloma or mediastinal tumor. In case of difficult preoperative diagnosis of a para-esophageal mass, endoscopic ultrasound was a safe and very useful procedure to clearly distinguish cystic from solid masses as well as defining the intraextramural extent of the lesion. In our case, we focused on the differentiation with a diverticulum if communication was of coexistence.
All suspected bronchogenic cysts were suggested to be removed in operable candidates. Because complete surgical resection would contribute to establish diagnosis, alleviate symptoms, and prevent complications. We considered the connection in our case was a congential communication, instead of fistula formation. The operation procedures were simple and it's unnecessary to suture the mucosa, and submucosa tissue, respectivelly. Full-layer suture of the neck of canal along esophageal wall in twice was enough for a safe repairment. Embrace with omentum or chest pleural are unnecessary, which may be suitable in suspected individual with severe infection[9, 18].