Gallbladder Ciliated Foregut Cyst Suspected of Malignancy Preoperatively

Background Gallbladder ciliated foregut cysts (CFCs) of the lower diaphragm are extremely rare. Furthermore, they are rarely suspected of malignancy preoperatively. Case Presentation. A 50-year-old woman was referred to our hospital for further examination and treatment of a gallbladder tumor that was detected using abdominal ultrasonography (US). After a close inspection, she was diagnosed with a gallbladder tumor that was possibly malignant. Accordingly, open whole layer cholecystectomy was performed because intraoperative US revealed a tumor located on the intraperitoneal side of the gallbladder, and a rapid intraoperative pathological diagnosis identified no malignancy. A postoperative pathological examination revealed a cystic lesion with thin walls covered with ciliated epithelium, which laid on a connective tissue with smooth muscle fibers. Based on the above results, the final pathological diagnosis was CFC of the gallbladder without malignancy. Conclusions Cases of gallbladder CFC can be considered as cysts requiring treatment owing to CFCs' potential for malignant transformation and high-frequency symptoms.


Introduction
Ciliated foregut cysts (CFCs) are rare congenital cysts arising from the remnant embryonic foregut and are usually located above the diaphragm [1]. Most CFCs located below the diaphragm are found in the liver. However, CFCs of the lower diaphragm are rarely found in the gallbladder [2,3]. The biological behavior of these CFCs remains to be clarified because of their rarity. Furthermore, gallbladder CFCs are rarely suspected of malignancy preoperatively. Herein, we report on an extremely rare case of CFC of the gallbladder suspected to be a malignant tumor preoperatively.

Case Presentation
A 50-year-old woman was referred to our hospital for further examination and treatment of a gallbladder tumor detected using abdominal ultrasonography (US). She had no history of malignancy, and physical and laboratory examinations, including tumor marker tests, revealed no specific findings. Contrast-enhanced computed tomography (CT) revealed a 20 mm lesion that was contrasted in the neck of the gallbladder, which had an unclear border with the liver (Figures 1(a)-1(c)). No enlarged lymph nodes or distant metastases were observed. Endoscopic US showed an isoechoic lesion on the intraperitoneal side of the gallbladder without a broken gallbladder wall (Figure 1(d)). Magnetic resonance imaging (MRI) was not performed because the patient was claustrophobic.
These results suggested that it could be gallbladder cancer. Accordingly, open whole layer cholecystectomy without lymph node dissection and hepatectomy were performed because intraoperative US revealed that the tumor was located on the intraperitoneal side of the gallbladder, and rapid intraoperative pathological diagnosis identified no malignancy. A macroscopic examination of the resected specimen showed a gross appearance of a submucosal tumor    3 Case Reports in Surgery in the neck of the gallbladder, and the tumor was found to be a unilocular cyst filled with mucoid liquid (Figures 2(a) and 2(b)). A postoperative pathological examination revealed a cystic lesion with thin walls covered with ciliated epithelium, which was laid on a connective tissue with smooth muscle fibers (Figure 3(a)). It was clearly separated from the gallbladder and located just outside the gallbladder wall without luminal communication (Figure 3(b)). Additionally, the lesion did not show any malignant findings. Based on the above results, the final pathological diagnosis was gallbladder CFC. Her postoperative course was uneventful, and the patient was discharged in a good condition.

Discussion
CFCs are congenital lesions that develop in the anterior primitive intestine. They are usually found above the diaphragm as cysts on the bronchi or esophagus [1]. Below the diaphragm, they are generally present in the liver and known as ciliated hepatic foregut cysts [2]. However, CFCs of the gallbladder are extremely rare. Only 13 cases of CFC of the gallbladder, including the present case, have been reported till date [1,[4][5][6][7][8][9][10][11][12][13][14] ( Table 1). The median age was 39 years, with a range of 9-72 years. Ten of the thirteen patients were female. The most frequent clinical symptom was abdominal pain, seen in nine cases. The most frequent location was the neck, which was reported in nine cases, followed by the body in three cases. The median size of the cysts was 27 mm, with a range of 7-45 mm. Ten out of the 13 cases had a cyst with mucous content. All cases, including the present case, were pathologically diagnosed with gallbladder CFC.
It is often difficult to radiographically distinguish between benign and malignant CFCs. Most cases of gallbladder CFCs reported anechoic features on US and nonenhanced findings on CT [1,[4][5][6][7][8][9][10][11][12][13][14] (Table 1). In the present case, CT revealed a contrast-enhanced lesion with an unclear border along the liver, suggesting the possibility of malignancy. In MRI, gallbladder CFCs frequently show hyperintensity in T1 and T2 sequences, but sometimes, these appear isointense or hypointense in T1 sequences, which can be helpful in the diagnosis of CFCs of the gallbladder [15]. Furthermore, Han et al. [11] reported that MRI was superior to other modalities in diagnosing cystic lesions. In the present case, malignancy could have been ruled out if the lesion could be evaluated using MRI; however, MRI was not performed due to the patient's claustrophobia. Therefore, MRI may allow differentiation between benign from malignant CFCs of the gallbladder, especially when the possibility of malignancy cannot be ruled out.
It remains to be clarified whether open surgery or laparoscopic surgery is the best procedure for CFCs of the gallbladder, although a recent guideline for biliary tract cancers recommended laparotomy for patients with suspected gallbladder carcinoma [19]. A literature search [1,[4][5][6][7][8][9][10][11][12][13][14] (Table 1) revealed that the most frequent surgical procedure was laparoscopic surgery, which was performed in 6 cases, followed by open surgery. Therefore, open surgery may be a better surgical procedure if malignant CFS is suspected, and laparoscopy if symptomatic but benign CFC is suspected. In recent years, single-port laparoscopic cholecystectomy has become popular due to its superior cosmetic appearance [20]. The surgical procedure may be indicated in CFC cases, which are relatively common in young women. Further investigation is needed to identify the appropriate procedure for CFCs of the gallbladder.

Conclusions
This report describes an extremely rare case of gallbladder CFC suspected of gallbladder cancer preoperatively. The present findings suggest that gallbladder CFCs can be considered as cysts requiring treatment due to their potential for malignant transformation and high-frequency symptoms.

Data Availability
The [DATA TYPE] data used to support the findings of this study may be released upon application to the [DATA ACCESS COMMITTEE NAME or INSTITUTIONAL REVIEW BOARD NAME], who can be contacted at [CON-TACT DETAILS].

Consent
Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Conflicts of Interest
The authors declare no conflicts of interest. 4 Case Reports in Surgery