Choledochal Cysts

by Richard Mitchell, MD, PhD

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    00:01 All right then. Let's look at choledochal cysts.

    00:04 These are congenital bile duct anomalies caused by dilation and/or obstruction of the biliary tree.

    00:11 And it's pretty straightforward once you've identified what it is.

    00:16 There are different types, type one to type five, do you need to memorize this? Absolutely not. Know that type one, I guess, is the most common.

    00:24 This is cystic dilation of the extrahepatic duct and then, there are just a diverticulum of the common duct.

    00:32 There is a choledochocele, that's a duodenal wall common duct cyst.

    00:40 So, at the point where it enters into the duodenum, there's dilation of both the intra and extrahepatic ducts.

    00:47 And then, least common overall, cystic dilations of the intrahepatic ducts.

    00:52 Again, do you need to memorize this? No. Just realize that there's going to be pathology associated with anything other than the nice narrow normal common bile duct.

    01:05 The epidemiology of this. So, it's relatively rare, one in 100,000 to 150,000 in Western industrialized countries because of a genetic founder effect. It's more common, one in 1,000 in the Asian population.

    01:21 The male to female ratio is one to three to four, so, females, much more common and it's often diagnosed in infancy or childhood because of obstruction of bile flow.

    01:33 The etiology of this, the vast majority of cases, it's congenital.

    01:38 You were born that way because of a developmental defect.

    01:41 It can be rarely acquired after cholecystectomy, so, damage to the bile duct wall during removal of the gall bladder can lead to the formation incidentally of a choledochal cyst.

    01:56 It may be associated with other anatomic variants.

    01:59 So, if there is an abnormal junction of the pancreas into the biliary tree, if there are areas of biliary or duodenal or colonic atresia that may cause secondary choledochal cysts and when there is a common bile duct reduplication that is frequently associated with these cysts.

    02:22 How does it present? Well, it presents primarily with obstructive jaundice and in infants, because they can't really tell you what's going on, there's a palpable mass.

    02:34 There's hepatomegaly because you're not dumping bile appropriately into the GI tract at the duodenum because of obstruction due to the cyst, the stools tend to be light-colored and you will tend to have increased bilirubin within the urine, so, it'll be darker urine.

    02:51 And it's usually an incidental finding but it comes to light because of the obstructive jaundice.

    02:59 In children, usually, before their teenage years, it will manifest with pain and nausea, vomiting and fever.

    03:06 There'll be jaundice and with higher levels of bilirubin, there may also be deposition of bile salts causing pruritus.

    03:13 There will often be a palpable mass, this dilated duct system can be felt.

    03:18 And because of the location, you can also get obstruction of pancreatic duct release of contents and get recurrent bouts of pancreatitis.

    03:31 The diagnosis is largely clinical but we will also do confirmatory laboratory testing.

    03:36 The liver is doing its job. So, it is conjugating the bilirubin just fine but we have elevated levels of the conjugated direct hyper - of bilirubin because we're not able to get it into the GI tract because it's obstructive.

    03:52 We also see elevated alkaline phosphatase, a good marker for either intrahepatic or extrahepatic biliary tree obstruction is the alkaline phosphatase.

    04:02 Overall in most cases, there's not much hepatocyte damage.

    04:07 So, the transaminases, ALT and AST, will be mildly elevated at most.

    04:13 Ultrasonography will be your prime way of doing the diagnosis.

    04:16 You will see a dilated duct either intrahepatic, extrahepatic or some combination of both.

    04:22 And then, you can also do ERCP, the endoscopic retrograde cholangiopancreatography to actually visualize what is going on in the biliary tree.

    04:32 How are we going to take care of this? Well, if there are complications with severe obstruction, particularly, in infancy and/or severe liver dysfunction, we can get coagulopathy and we need to minimize those risks. Not only that but with the choledochal cysts, you will often get associated inflammation, inflammation with regenerating epithelium is prime territory for developing cancer. So, there's a risk of cholangiocarcinoma.

    05:04 Surgically, we will intervene. We can cut out the cyst and do a primary anastomosis.

    05:10 We can also do bile to enteric direct connections.

    05:15 And with that, we finished our discussion of choledochal cysts.

    About the Lecture

    The lecture Choledochal Cysts by Richard Mitchell, MD, PhD is from the course Disorders of the Biliary Tract.

    Included Quiz Questions

    1. Cystic dilation of the extrahepatic duct
    2. Common duct diverticulum
    3. Common duct cyst of the duodenal wall
    4. Dilation of both intrahepatic and extrahepatic ducts
    5. Cystic dilation of intrahepatic ducts
    1. Nonpalpable mass
    2. Obstructive jaundice
    3. Hepatomegaly
    4. Dark-colored urine
    5. Light-colored stools
    1. Cholangiocarcinoma
    2. Hepatocellular cancer
    3. Pancreatic cancer
    4. Anemia
    5. Thrombocytopenia

    Author of lecture Choledochal Cysts

     Richard Mitchell, MD, PhD

    Richard Mitchell, MD, PhD

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