Choledochal Cysts Types | Type 1, Type 2, Type 3, Type 4a, Type 4b, Type 5

A choledochal cyst is a condition that occurs in the tubes (ducts) that transport bile from your child's liver to their gallbladder and intestines. The tubes dilate or pouches develop on the tubes, making them larger than usual. This prevents bile from moving freely, which may result in liver issues.

Bile is a liquid that plays an important role in the digestive process by assisting in the breakdown of lipids. Normally, bile enters larger ducts from small bile ducts in the liver. Bile then exits the liver via two major ducts. These ducts connect together outside the liver to form the common bile duct.

The liver and gallbladder are linked by the common bile duct, which also links the gallbladder to the small intestine. The gallbladder is responsible for storing bile until it is required by the digestive process to break down food. The gallbladder is stimulated to contract and squeeze bile into the gut when food is consumed.

Bile flow can be blocked by cysts. The bile ducts may swell, become infected, or become irritable (inflamed) when bile does not flow normally. It is known as cholangitis. It can lead to liver scarring (cirrhosis) over time. The liver is then unable to function properly. Children affected by choledochal cysts may also develop pancreatitis.

Choledochal Cyst Types

Choledochal Cyst Type 1

Cystic dilatation of the common bile duct is a hallmark of Type 1, which account for 50 to 80% of choledochal cysts. Type 1 choledochal cysts are thought to be caused by a congenital impairment or malformation of the bile duct wall, while the exact reason is unknown. This kind of cyst can result in consequences such as bile duct obstruction, infection, and inflammation.

Choledochal Cyst Type 1a

The entire extrahepatic biliary tree has cystic dilatation in Type 1a, and the pancreaticobiliary junction is abnormal. Type 1a cysts, like other varieties of choledochal cysts, can result in issues like bile duct obstruction, infection, and inflammation. The choledochal cyst type 1a can be treated by surgical removal of the cyst, followed by repairing the bile duct to make sure adequate bile outflow after the removal of the cyst.

Choledochal Cyst Type 1b

The extrahepatic biliary tree is segmentally dilated in Type Ib, although there is no abnormal pancreaticobiliary junction. Cysts of type 1b are distinguished by a thick-walled dilatation and have a spherical or sac-like shape. Inflammation, infection, and obstruction of the bile duct are just a few of the issues that can arise from a choledochal cyst of type 1b variety.

Choledochal Cyst Type 1c

Type 1c is characterized by diffuse fusiform dilation of the entire extrahepatic biliary tree as well as an abnormal pancreaticobiliary junction. 

Choledochal Cyst Type 2

Type 2 cysts make up 2% of choledochal cysts. It entails the dilation of diverticular tissue anywhere along the extrahepatic duct.

Choledochal Cyst Type 3 

About 1.4% to 4.5% of choledochal cysts are classified as type 3 cysts, which are also referred to as choledochocele. It entails intraduodenal cystic dilatation of the distal common bile duct.

Choledochal Cyst Type 4

It is estimated that 15% to 35% of choledochal cysts are type 4 cysts and that these cysts tend to be multiple. The extrahepatic and intrahepatic bile ducts both exhibit numerous cystic dilations, as well as abnormalities and strictures.

Choledochal Cyst Type 4a

Multiple dilations, involving both the intrahepatic and extrahepatic branches of the biliary system, are characteristic of type 4a.

Choledochal Cyst Type 4b

Multiple dilations that are restricted to the extrahepatic biliary tree are characteristic of type 4b.

Choledochal Cyst Type 5

Approximately 20% of choledochal cysts are classified as type 5 cysts, which are also referred to as Caroli's disease. It entails a number of dilations that are restricted to the intrahepatic biliary tree. The Caroli syndrome is characterized by both type V choledochal cysts and congenital hepatic fibrosis.