Choledochal cyst originating from the cystic duct is a very rare case and difficult to diagnose preoperatively, it is classified as Todani type VI choledochal cyst. Only three cases of type VI choledochal cyst have been reported in the literature.
A 35-year-old woman came with an enlarged and palpable mass in the right upper abdomen. The initial abdominal contrast CT scan and MRCP supported the presentation of Todani type 1 choledochal cyst. Intraoperatively, In different diagnosis, it was not type 1 but Todani type VI choledochal cyst. A large cyst originating from the cystic duct, attached to the gallbladder was found, without any connection to the intra or extrahepatic bile duct. The patient underwent simple cholecystectomy as well as excision of the cyst. After the follow-up for 3 months, the patient was uneventfully cured.
Preoperative diagnosis of type VI choledochal cyst seems to be difficult because it is a rare entity and it exhibits an ambiguous anatomic feature. Most cases may be misidentified as type I or II choledochal cyst before surgery. The diagnosis was made intraoperatively. Preoperatively the definitive anatomy may be delineated by ERCP if there is any high suspicion.
Conclusively, preoperative diagnosis of type VI choledochal cyst may be challenging and requires detailed radiological evaluation and multidisciplinary discussion. The cystic duct orifice and the diameter of the common bile duct are important to determine adequate management during the operation.
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