Content created by Nicolas Jabbour, M.D., NZTI medical director
and Sharad Sharma, M.D., research fellow.

Introduction

Choledochal cysts are congenital dilatations of the intrahepatic and extrahepatic biliary tree. The Todani modification of the Alonso-Lej classification of choledochal cysts is the system most often used for diffentiating and planning management of these cysts.
 
The frequency of diagnosis seems to be increasing, probably because of improvements in abdominal imaging. These cysts although uncommon in the western hemisphere, are common in Japan. Histologically the cyst wall is made up of fibrous tissue suggesting the role of chronic inflammation in the pathogenesis.

Types of choledochal cysts

• Type I cysts represent approximately 85% of most series. They are fusiform in shape.
  
  

  This diagram shows the normal anatomy of the liver, pancreas, and the bile duct.

  Diagrammatic description of the type 1 choledochal cyst showing the fusiform dilatation of the bile duct.

  
  
  
• Type II cysts represents less than 2% of cases, and are often called common bile duct diverticulum.
  
  

  This is a type 2 cyst,  saccular dilatation of the bile duct.

   
   
• Type III cysts also called choledochoceles represents approximately 2% of cases, here the dilatation is localized to the terminal portion of the biliary tract
  
  

  This shows the type 3 choledochal cyst, here the dilatation isconfined to the terminal portion of the bile duct.

  
  
• Type IV cysts represent the remaining approximately 10% of cases.(here the dilatation affects both intrahepatic and extrahepatic bile ducts
  
  

  This shows the type 4 cyst, here the disease affects both of the ducts within and outside of the liver.

  
  
   
• Type V cysts are Caroli's disease .They are purely intrahepatic in nature, and the association with cancer though present is weak than the rest of the group. They are frequently associated with portal hypertension and congenital hepatic fibrosis
  
  

  This is called Carolis disease. Here, the dilation of the ducts is confined to intrahepatic portion only.

   

Clinical features

• The cysts although congenital in nature usually manifest themselves in childhood but they can present anytime in the life. Only approximately 20% of cases manifest themselves in adults. Neonates usually present with jaundice and a mass in the abdomen
• In the first decade of life, ascending cholangitis (infection of the biliary tract) is a more likely manifestation. 
• Manifestation in adulthood includes several years of vague right upper quadrant abdominal pain. At the time of diagnosis adult patients usually have an associated complication like one of the following

Complications

• Jaundice(jaundice occurs because the dilated ducts do not drain adequately , as a result the billirubin in the blood increases
• Pancreatitis (inflammation of the pancreas gland, characterized by severe abdominal pain ,loss of appetite and nausea and vomiting ) 
• Spontaneous cyst rupture( the bile is usually infected and on rupture leaks into the peritoneum and may result in biliary peritonitis with a reported high mortality ) 
• Biliary cirrhosis( normal liver tissue is gradually replaced by fibrous tissue ) 
• Signs of portal hypertension including variceal bleeding and ascites 
• Without therapy for choledochal cysts, biliary cancer, usually cholangiocarcinoma develops in approximately 15% to 20% of patients older than 20 years. The incidence of cancer keeps on increasing with age and reaches 50% by 50 years The most common site of the cancer is the cyst wall, but as many as 40% of cases it can occur at other sites in the liver or pancreas, especially the gallbladder. For this reason and to prevent future gallbladder-related symptoms, cholecystectomy is usually performed during cyst surgery.

Diagnosis

• Ultrasonography, CT, (these tests are frequently used as the first test, they help in not only diagnosing the condition but they also help in defining the type of the cyst.)
  
  

  This is a an MRI showing the enlarged cyst and the gall bladder containing the multiple stones.

   
  
• Hydroxy iminodiacetic acid (HIDA) imaging(displays the dilated duct and the delayed transit of the bile through the duct ) 
• Endoscopic retrograde cholangiography or PTC (this test is used infrequently now, as the same information can be gathered by MRCP which is noninvasive in nature) 
• Magnetic resonance cholangiography shows characteristic dilatation of the biliary tree.
  
  

  MRI of the abdomen again showing the cyst (white in color on the T2 images).

  
  
• Liver function tests may show elevated alkaline phosphatase, total bilirubin, and γ-glutamyl transpeptidase levels consistent with biliary obstruction. Hepatic fibrosis is often associated with choledochal cysts, especially Caroli's disease, can be diagnosed by a live biopsy.

Causes

• There are several theories about their etiology, although the true cause of choledochal cysts remains unclear. The most accepted theory states that the high insertion of the common bile duct into the pancreatic duct leads to reflux of pancreatic juice into the biliary tree. This leakage causes weakening of the bile duct wall, inflammation, and fibrosis. The distal bile duct becomes obstructed and therefore results in proximal dilatation with cyst formation.
• There appears to be a high rate of anomalous pancreaticobiliary duct junction in the range of 90% in most series.

Treatment

• Management of choledochal cysts is based on the type of cyst according to the Todani classification .Irrespective of the presence or absence of symptoms the treatment includes cyst excision (removal)...
  
  

  Portion of the cyst and the duct which has to resected in the surgery. In addition, gall bladder is always removed prophylactically as there is a risk of cancer.

   
  
  ...to prevent the complication of subsequent cancer formation. Only type III, IV and type V can be left in situ as there risk of development of cancer is low .Internal drainage of the cyst frequently results in inadequate drainage and accelerates the subsequent development of the cancer .The first objective of treatment is to obtain adequate drainage and antibiotic coverage for any patient with signs and symptoms of cholangitis. This may be achieved with PTC or ERCP.
• The current standard of practice for type I and II choledochal cysts is complete cyst excision with anastomosis of the bifurcation of the hepatic ducts, common hepatic duct, or common bile duct with Roux-en-Y anastomosis to the jejunum

This is an operative photograph showing the dilated bile duct (choledochal cyst) along with the liver and gall bladder.

Delination of the common hepatic duct.

Operative photographs showing the exposure and delineation of the ductal opening after opening the cysts.

Operative photographs showing the inside of the cyst and cannulating the distal part of the bile duct toward the pancreas

Operative pictures showing the hilum of the liver and the ducts after the cyst excision. the probe is inside the most diatal part of the duct. it is important to protect the pancreatic duct at this level.

The final appearance after the operation, cyst had been excised along with cholecystectomy, and the reconstruction is done by roux en y hepaticojejunostomy.

This is the resected specimen showing the gall bladder and the dilated cyst, in addition multiple stones can be seen.

• Patients who have previously undergone drainage procedure of the cyst need complete cyst excision with Roux-en-Y hepaticojejunostomy.
  
  
  
• Type III choledochal cysts are also called choledochoceles. Choledochoceles rarely develop into cancer, and therefore complete excision may not be mandatory. Large cysts should be excised either partially or completely and the ducts reanastomosed to the duodenum. Small choledochoceles can be managed with endoscopic sphincterotomy. 
• Type IV choledochal cysts with both intrahepatic and extrahepatic components make total cyst excision difficult. Total excision of the extrahepatic cysts can usually be accomplished, and anastomosis with the enteric tract should be performed at the hilum to prevent a high rate of anastomotic strictures. Partial hepatectomy, if technically feasible, has also been advocated for the removal of intrahepatic cysts because of malignant potential. The risk of biliary cancer in the retained intrahepatic cysts is not known but is probably low 
• The presence of type V cysts, also known as Caroli's disease, results in multiple intrahepatic biliary cysts and makes treatment more difficult. Complete resection of biliary cysts is usually impossible because of the location of the cysts. For this reason, conservative treatment of cholangitis with antibiotics is usually the initial choice. Rotating antibiotics to suppress episodes of cholangitis is advisable. If the cysts are superficial and limited in number, hepatic resection can sometimes be curative. .Liver transplantation is generally reserved for patients with hepatic failure. Prognosis is much worse for this type of choledochal cyst than for the others.

(All the operative photographs are taken from the personal archives of Dr Jabbour; the diagrammatic pictures were created  by Dr. Nicolas Jabbour and Dr. Sharad Sharma)