Bile duct cyst
 Discussion of Bile duct cyst
- According to the Todani system, there are five types of bile duct cysts.
 Type 1: Choledochal Cyst
- Account for 80% to 90% of all bile duct cysts
- Characterized by fusiform dilation of the extrahepatic bile duct
- Theorized that choledochal cysts form as the result of reflux of pancreatic secretions into the bile duct via anomalous pancreaticobiliary junction.
- Cyst should be resected completely to prevent associated complications (i.e. ascending cholangitis and malignant transformation).
 Type 2: Diverticulum
- Account for 3% of all bile duct cysts
- Represent a true diverticulum.
- Saccular outpouchings arising from the supraduodenal extrahepatic bile duct or the intrahepatic bile ducts.
 Type 3: Choledochocele
- Account for 5% of all bile duct cysts
- Represent protrusion of a focally dilated, intramural segment of the distal common bile duct into the duodenum.
- Choledochoceles may be successfully managed with endoscopic sphincterotomy, surgical excision, or both, in symptomatic patients.
 Type 4: Multiple Communicating Intra- and Extrahepatic Duct Cysts
- Second most common type of bile duct cysts (10%)
- Subdivided into subtypes A and B.
- Type 4A: Fusiform dilation of the entire extrahepatic bile duct with extension of dilation of the intrahepatic bile ducts
- Type 4B: Multiple cystic dilations involving only the extrahepatic bile duct.
 Type 5: Caroli's Disease
- Caroli's disease is a rare form of congenital biliary cystic disease manifested by cystic dilations of intrahepatic bile ducts
- Association with benign renal tubular ectasia and other forms of renal cystic disease.
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 References for Bile duct cyst
- Yu, Jinxing, Turner, Mary Ann, Fulcher, Ann S., Halvorsen, Robert A. Congenital Anomalies and Normal Variants of the Pancreaticobiliary Tract and the Pancreas in Adults: Part 1, Biliary Tract. Am. J. Roentgenol. 2006 187: 1536-1543