Bile duct cyst: (Choledochal cyst)
Choledochal cysts represent congenital disproportionate cystic dilatations of the biliary tree.
Choledochal cysts are rare, with an incidence of 1 :100000 – 150000. Although they may be discovered at any age, 60% are diagnosed before the age of 10 years . There is a strong female predilection with a M : F ratio of 4 : 1. There are 5 main types, with several sub types.
The aetiology is uncertain but a close association with anomalous formation of the pancreaticobiliary ductal junction is reported in some subtypes .A number of associations are recognized, including biliary atresia, hepatic fibrosis, associated with type V (Caroli disease)
Diagnosis relies on the exclusion of other conditions as a cause of biliary duct dilatation: (i.e. tumour, gallstone or inflammation as the cause).Classically presentation includes the triad of symptoms; abdominal pain, jaundice & abdominal mass. This triad is however only present in 19 – 60% of cases.
Imaging of the biliary tree can be achieved with ultrasound, MRCP, and CT scan. Direct contrast studies as ERCP should be avoided and only to be done in doubtful cases, provided there is no biliary obstruction and cholangitis.
Complications: Complications include: stone formation (most common),malignancy (cholangiocarcinoma) life time incidence 10 – 15%, cyst may rupture leading to bile peritonitis, (most frequently seen in neonates) and pancreatitis.
Treatment : The only feasible treatment is surgical excision, with biliary reconstruction. A number of possible approaches exist, depending on cyst location.