25 years old female with chronic right upper quadrant abdominal pain

History
25 years old female with chronic right upper quadrant abdominal pain.

Imaging findings
Portal venous phase contrast-enhanced MRI shows multiple liver lesions compatible with metastases (A). In MRCP, cystic dilatations of extrahepatic bile ducts including common hepatic duct and common hepatocholedochal duct (B, arrows) are visible. Coronary T2-weighted imaging (C) and coronal portal venous phase contrast-enhanced MRI show ductal wall thickening within the cyst around the orifice of the cystic duct (arrows). The ADC map indicates restricted diffusion in this area (E, circle). Best visible in arterial phase contrast-enhanced MRI, there is pancreas divisum with a small duct connecting main pancreatic duct and bile duct (F, G). Follow-up imaging demonstrates progression of ductal wall thickening (H).

Diagnosis
Metastatic cholangiocarcinoma of extrahepatic bile duct with choledochal cyst type Todani 4b and (incomplete) pancreas divisum.

Discussion
Biliary cysts (BC) are rare dilatations of the biliary tract and may affect the intrahepatic and extrahepatic bile ducts. The incidence is higher in Asia than in western countries, and women are more commonly affected. Cholangiocarcinoma is the most serious complication and is observed in up to 30% of patients with BC. The risk of biliary cancer increases with age. Cholangiocarcinoma in patients with BC occurs about 20 years earlier than in the general population.

BC are classified according to Todani. Five types are distinguished on the basis of imaging appearance. The most frequent is type 1 (more than 90%).

  1. BC of extrahepatic bile duct
    • a: Marked cystic dilatation of entire extrahepatic bile duct
    • b: Focal dilatation of extrahepatic bile duct usually distal to cystic duct insertion
    • c: Fusiform dilatation of entire extrahepatic bile duct
  2. Diverticulum of extrahepatic bile duct
  3. Dilatation of common bile duct confined to duodenal wall (choledochocele)
  4. Multiple BC
    • a: Extrahepatic and intrahepatic bile ducts
    • b: Extrahepatic bile duct only
  5. Caroli-disease and Caroli-syndrome (plus congenital liver fibrosis)

The pathogenesis of BC is still a matter of discussion. Intrahepatic BC are considered to result from embryologic ductal plate malformations. Extrahepatic BC (choledochal cysts) are supposed to occur secondary to congenital presence of an abnormal pancreaticobiliary junction (APBJ). APBJ can be observed in 50-80% of patients with BC and refers to an early anomalous union of bile and pancreatic duct outside the ampulla of Vater with formation of a so-called common channel. Different patterns of APBJ are described in the Komi classification, in which the in our case present pancreas divisum represents APBJ type 3a. APBJ is suggested to lead to pancreaticobiliary reflux, inflammation and dilatation of the bile duct wall and development of biliary tract dysplasia. BC should be treated with surgery upon detection to prevent malignancy. The goal of surgical treatment is to remove the cyst and to reconstruct the proper bile flow to the alimentary tract.

Recommended reading
Jablonska
Biliary cysts: etiology, diagnosis and management
World J Gastroenterol 2012; 18(25):4801

Santiago et al.
Congenital cystic lesions of the biliary tree
AJR 2012; 198(4):825

provided by Tim

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