Choledochal Cysts

What are choledochal cysts?

A choledochal cyst is a rare congenital (present at birth) dilation of the hepatic or bile duct of the liver, the tract which transports bile produced by the cells to the gallbladder and duodenum. (See description of liver below)These cysts can be intrahepatic, meaning that they occur in the part of the duct located inside of the liver. They can also be extrahepatic, meaning part of the bile duct that is located outside the liver.

The liver

The liver is located in the upper right-hand portion of the abdominal cavity, beneath the diaphragm and on top of the stomach, right kidney, and intestines. The liver, a dark reddish-brown organ that weighs about three pounds, has multiple functions. The liver consists of two main lobes, both of which are made up of thousands of lobules. These lobules are connected to small ducts that connect with larger ducts to ultimately form the hepatic duct, sometimes known as the biliary tract. The hepatic duct transports bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine). which helps to break down fats, preparing them for further digestion and absorption. All of the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down the nutrients and drugs in the blood into forms that are easier to use for the rest of the body. For more information on the liver, see Anatomy of the liver There are five types of choledochal cysts, which are classified as the following:

Type 1 Cysts

This is the most common type, making up about half of all choledochal cysts. This type is a cystic dilation of the extrahepatic bililary duct.

Type 2 Cysts

This type of cyst is an abnormal pouch or sac (diverticulum) opening from the duct

Type 3 Cysts

This type involves a cyst that is located within the duodenal wall

Type 4 Cysts

This type refers to cystic dilations of both the intrahepatic and extrahepatic biliary tracts.

Type 5 Cysts

This is the least common type of hepatic duct cyst, which involves multiple intrahepatic cysts. This type of clustering of cysts is also known as Caroli's disease

How often do choledochal cysts occur and what causes them?

Choledochal cysts occur in between 1 and 100,000 and 1 in 150,000 people in Western countries but is much more common in Japan. They are three to eight times more common in females than males. Choledochal cysts do frequently present during childhood but they are more commonly diagnosed in adulthood. The cause of these cysts is unknown, but researchers believe that their formation is due to an abnormal connection between the pancreatic and hepatic ducts. This abnormal connection leads to a reflux of pancreatic juice into the biliary tract, which could be responsible for cyst formation.

What are the symptoms of choledochal cysts?

The following symptoms of choledochal cysts are usually experienced by an older child whose earlier diagnosis of this congenital anomaly may have been missed. These symptoms may be experienced differently by different patients or they may be indicative of another condition. Always consult a physician for a diagnosis: Right upper quadrant pain Jaundice Abdominal mass Nausea Fever Pancreatitis

Choledochal cysts can be diagnosed prenatally. Doctors may notice a right upper quadrant cystic mass on a prenatal ultrasound. During the neonatal period, you or your child's doctor may notice a right upper quadrant mass, with or without jaundice. Your child will likely undergo a combination of the following tests: computerized tomography scan (CT or CAT scan) A diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called "slices") both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including bones,muscles, fat and organs. CT scans are more detailed than general x-rays. Cholangiography: radiographic visualization of the bile ducts after ingestion or injection of a radiopaque substance Surgery: If choledochal cysts are suspected, a pediatric surgeon will perform exploratory surgery to further establish the anatomy of the biliary duct system. At this point, the pediatric surgeon will also remove the cyst or cysts. This could involve removing of a lobe of the liver if the cyst is intrahepatic, or part of the extrahepatic duct, followed by duct reconstruction using a piece of intestine. Without surgery, there is an ongoing risk of biliary obstruction and secondary cholangitis, jaundice, and cirrhosis. Another long-term concern is for malignant degeneration. Choledochal cysts are inflammatory in nature, which makes them at risk for cancer if left untreated. The pediatric surgeon may decide only to remove the cyst lining, to protect the underlying portal structures. Once the cyst or cysts are surgically removed, the biliary duct requires reconstruction. This could involve surgical creation of a passage uniting the common bile duct and the small intestine using a piece of small intestine.