Choledochal cysts were first described by Vater in 1723.¹

Anatomic variations of choledochal cyst were later classified by Alonso-Lej et al in 1959.² Subsequently, Todani et al classified choledochal cysts into 5 major types and multiple subtypes. This is the most commonly used classification system today.³

Described in literature up through the 1970s a cholecystoenterostomy was considered a surgical management option for choledochal cysts.⁴,⁵

Cyst excision with hepaticoenterostomy is now the favored procedure. This reduces the chance of pancreatitis,⁶ malignancy in the remaining cyst,⁶ and cholangitis.⁷

Type I (most common): consists of dilatation of the common bile duct, which may be cystic, focal, or fusiform (subtypes A, B, and C, respectively)

Type II: a saccular diverticulum off the common bile duct

Type III: a cystic dilatation of the intramural portion of the common bile duct (may represent a duodenal diverticulum rather than a choledochal cyst)

Type IV-A (second most common): both intrahepatic and extrahepatic dilatation of the biliary tree

Type IV-B: Multiple extrahepatic cysts

Type V: “Caroli disease”; multiple intrahepatic biliary dilatations (Figure 20.1)

1 in 100 000 Western individuals⁹

1 in 13 000 people within the Japanese population⁹

Females are affected more frequently. Male-to-female ratio in both children and adults is approximately 1:4.¹⁰,¹¹

The most universally accepted theory is that pancreatic juice refluxes into the biliary system, causing increased pressure within the common bile duct that leads to ductal dilatation.¹²

They are associated with an anomalous pancreatobiliary junction with a long common channel (>15 mm).

Additionally, abnormal function of the sphincter of Oddi has been reported to predispose to pancreatic reflux into the biliary tree, which may be associated with choledochal cysts.¹³