Laparoscopic management of a cystic duct cyst

Background: Choledochal cysts are rare cystic dilatations of the biliary tree. Though their cause is uncertain, these cysts are usually referred for surgical resection because of their association with developing malignancy. Traditionally choledochal cysts have been classified under 5 main types. Not included in this classification are cysts of the cystic duct, a condition that is even rarer, with only 14 cases reported in the literature to date. We describe one such rare case of a cyst of the cystic duct that we successfully treated via laparoscopic resection. Methods and Results: A 41-year-old male was found to have a biliary abnormality on a routine follow-up computed tomography (CT) scan for an unrelated medical condition. Further magnetic resonance cholangiopancreatography (MRCP) imaging identified a cystic dilation consistent with a Type II choledochal cyst. Laparoscopic resection was performed using a total of 5 trocars, at which time a cyst of the cystic duct was found instead of the expected Type II choledochal cyst. Intraoperative cholangiography was used as a surgical adjunct to confirm the anatomy, and resection of the cyst was completed without complications. Conclusions: Our case adds to the body of reports showing that cysts of the cystic duct, while extremely rare, do occur and need to be recognized. Given the preoperative similarity between cystic duct cysts and other choledochal cysts, proposal for a new "Type VI" category for choledochal cysts may be considered so that clinicians can be prepared for this variation. Once recognized, cysts of the cystic duct can be safely and effectively removed by laparoscopic excision, as we have demonstrated.