Imaging of Choledochocele and Choledochal Cyst
Clinical features and pathophysiology
- Congenital cystic dilatations of the biliary tree.
- Clinical presentation: Triad of
- Abdominal pain
- Abdominal mass.
- Associated with: Biliary atresia and hepatic fibrosis.
- Complications: 3Cs of Choledochal Cyst
- Carcinoma (10-15% lifetime risk)
- Cyst rupture (peritonitis), pancreatitis.
- Treatment: Surgical excision with reconstruction.
Todani Classification of Choledochal Cyst
- Extrahepatic bile duct – Most common (77-87%)
- Extrahepatic bile duct diverticulum.
- Multiple cysts – Intra / extra. IVA – BOTH Intra and extrahepatic bile duct cysts. IVB: Only extrahepatic bile duct cysts.
- Only intrahepatic bile duct dilatation (Caroli’s disease).
Pathophysiology of Choledochal cyst
Anomalous pancreaticobiliary junction: Abnormal junction of the pancreatic duct and common bile duct that occurs outside the duodenal wall to form a long common channel (> ⁉️ mm -Watch the video for the answer).
Pathophysiology of Choledochal cysts : Long channel + Obtuse / right angle = Reflux of pancreatic juices into bile ducts-> Dilatation of Biliary tree and formation.
Komi Classification of Anomalous pancreaticobiliary junction
- Right angle union.
- Acute angle union.
- Complex pattern.
Image : Komi Classification of anomalous pancreaticobiliary junction
Imaging of Choledochal Cysts
Imaging pearl: Choledochal Cysts should follow bile duct signal on all imaging modalities
Ultrasound: Anechoic cystic lesions, which communicate with the biliary tract and SEPARATE from the gallbladder.
- Non-enhancing cystic structure at porta hepatis contiguous with the biliary tree
- Intramural cystic mass in the duodenal wall communicating with CBD (type III) as illustrated in the case above.
- Multiple intrahepatic/extrahepatic cysts communicating with bile ducts (type IV and V)
- MRCP is the ideal investigation and will show cystic dilatation of biliary tree and relationship (and communication) of cysts with adjacent bile ducts.
- Hypointense on T1WI, hyperintense on T2WI, without wall enhancement on post-contrast images – Signal follows biliary tree.
- The presence of abnormal wall hyperenhancement or thickening can be due to superadded infection or malignancy (particularly with nodular or irregular wall thickening).
Reference and further reading
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Last Updated on July 6, 2020