There are five types of choledochal cysts:
Type 1: Dilation of the common bile duct
Type II: Diverticulum of the common bile duct
Type III: Choledochocele
Type IV: Multiple intrahepatic and extrahepatic choledochocysts
Type V: Single or multiple intrahepatic cysts (Caroli's disease).
Source: Blackbourne LH, Fleischer KJ. Advanced Surgical Recall. Baltimore, Md: Williams & Wilkins; 1997:874.
July 2002. Arch Surg. 2002;137(7):793-000. doi:10.1001/archsurg.137.7.793