Choledochal cysts - type IVa


The findings are compatible with choledochal cysts ( type IVa ).

Choledochal cysts are an uncommon anomaly of the biliary system manifested by cystic dilatation of the extrahepatic or intrahepatic biliary tree or both. 

Choledochal cysts can be classified into five types 1 :

  • type 1 cyst: is most common, accounting for 80 - 90% of cases. It is divided into 
    • type 1A - cystic dilatation of the common duct.
    • type 1B - focal segmental common duct dilatation
    • type 1C - fusiform dilatation of the common bile duct.
  • type 2 cyst: accounts for about 2% of patients and consists of a true diverticulum arising from the common duct.
  • type 3 cyst: accounting for 1 - 5% of cases, consists of a  choledochocele and involves only the intraduodenal portion of the duct.
  • type 4 cyst: is divided into 
    • type 4A: multiple intrahepatic cysts and an extrahepatic cyst, which accounts for  19%  of cases
    • type  4B: multiple extrahepatic cysts, which are much less common.
  • type 5 cyst: or Caroli’s disease, consists of single or multiple intrahepatic biliary cysts. Approximately two-thirds of patients with Caroli’s disease also have the extrahepatic disease.