Choledochal cysts are segments of the biliary tree that have undergone local distention. It is a congenital condition.
Infants who present with clinically active choledochal cysts display jaundice and hepatomegaly, due to the obstruction of bile within the ducts. The condition should be promptly treated with surgical intervention, since a prolonged obstruction will lead to a cirrhotic and scarred liver, portal hypertension and ascites, as well as a considerable possibility of malignancy on the cystic wall .
Adult individuals who have choledochal cysts usually present with a sub-acute clinical symptomatology. The patient reports periodic jaundice, abdominal pain and occasional occurrences of cholangitis or pancreatitis, attributable either to the condition itself or the subsequent formation of gallstones .
The first step towards a successful diagnosis is, as always, a detailed medical history. The patient is expected to present with a clinical picture compatible with that of biliary obstruction (abdominal pain, jaundice, hepatomegaly etc.).
Diagnostically speaking, no laboratory tests can be used to accurately diagnose the condition. A complete blood count may show markers of inflammation, such as increased levels of neutrophils, and liver function tests can be used to evaluate hepatic functionality as a whole. Amylase and lipase blood levels indicate the presence of pancreatitis, if found elevated.
Imaging techniques, on the other hand, greatly contribute to the diagnosis of a choledochal cyst. Ultrasonography is an excellent method of choice, as it is non-invasive and allows for the detection of such a distention, even before birth . Caroli disease can also be diagnosed before birth with the use of ultrasonography . A CT or MRI scan can further illustrate the exact anatomical location of a cyst and its particular characteristics. More specifically, MRCP (magnetic resonance cholangiopancreatography) has been proven a great, non-invasive tool for the detection of defective pancreatobiliary junctions in patients who present with choledochal cysts .
Regarding invasive diagnostic methodology, if all the aforementioned techniques fail to produce accurate results, endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography may also be performed .
Choledochal cysts are surgically treated and should be completely excised. In addition, conservative, antibiotic treatment should be applied in the scheme for patients suffering from cholangitis or other complications.
Generally, almost every patient who presents with choledochal cysts should undergo a complete removal of the latter, followed by a new junction between the biliary duct and duodenum (anastomosis) . The sub-category of patients also suffering from portal hypertension usually are discouraged from surgical procedures, because of the increased mortality rates and morbidity associated with their condition. Also, patients with Caroli disease usually undergo not an excision of the entire cyst, but a hepatic lobectomy, provided that the liver's functionality has been evaluated. In cases where the cyst is adjoined to the portal vein and complete surgical resection is not possible, a surgeon will remove the mucosal layer of the cyst in order to eliminate the possibilities of cancerous tumor. Its serosal part is left intact.
Patients are expected to fully recover, once the dilatations have been surgically removed. Prognosis worsens when poor markers are present, such as old age, comorbidities etc. The only late complication worsening the prognosis involves the slight possibility of cancerous tumors, due the inadequate removal of the cyst or a previously undetected malignant condition. Still, the incidence of malignancy amounts to 0.7%-0.8% .
The precise cause which leads to the formation of choledochal cysts has yet to be determined. The condition is generally categorized under the wider group of diseases called fibropolycystic disorders. Specifically, Caroli disease and cysts that belong to type IVA are viewed as ductal plate abnormalities.
A defective junction between the pancreatic and biliary duct is believed to predispose an individual to choledochal cysts, due to the frequent reflux of pancreas-derived juice into the biliary duct . A defective sphincter of Oddi, the anatomical structure that prevents bile and pancreatic fluids from refluxing from the duodenum into the biliary duct has also been incriminated for the same reasons . A theory has also been suggested, stating that a malfunction of the autonomic nervous system could be the culprit behind choledochal cysts . Researchers detected significantly diminished numbers of ganglia on the bile ducts of patients presenting with choledochal cysts, in comparison to individual who suffered from some type of mechanical obstruction.
Distentions of the biliary tree are usually diagnosed during childhood . The condition itself is rare, with an incidence estimated at 1:100,000 to 1:150,000 live births. Women appear 4 times more frequently affected than men and there seems to be a growing incidence in the regions of East Asia.
The exact pathophysiological mechanisms involved in the initial stages of the condition remain unknown due to the unclear etiology of choledochal cysts. It is safe, however, to assume that more than one factors are implicated in the condition's pathogenesis .
It is believed that choledochal cysts are formed as a result of pancreatic enzymes refluxing into the biliary tree. A study examined patients who presented with choledochal cysts and discovered that almost every single patient displayed some anomaly in the region where the pancreatic and biliary duct are adjoined . A dysfunctional junction leads to reflux of the bile-pancreatic fluids mixture back into the biliary tree, whose epithelium is not suitable to host pancreatic secretions. The latter damage the biliary ducts, which are also believed to be congenitally weaker than those of healthy individuals; as a result, cystic dilatations emerge.
The formation of choledochal cysts cannot be prevented.
Bile fluid is produced by the liver. It initially flows within the intrahepatic ducts, which, upon exiting the liver, form the left and right hepatic ducts. They merge to form the common hepatic duct, which is joined with the cystic duct (emerging from the gallbladder) to form the common hepatic duct. The latter is joined with the pancreatic duct; thus, bile and pancreatic enzymes are released into the duodenum for digestive purposes in the ampulla of Vater.
Choledochal cysts are distentions of the bile ducts. It is a congenital condition. The defect is attributable to an unknown cause, which leads to the malformation of the ducts during fetal development. Their classification primarily centers on whether they are a regional distention or a structure separated from the duct itself. A further criterion assesses the location of the dilatations.
Classification of choledochal cysts :
Type I: up to 90% of choledochal cysts are categorized under type I. It encompasses 3 subtypes:
Type II: the distention is viewed as a separate structure from the extrahepatic duct (diverticulum).
Type III: The extrahepatic duct is distended in the region of its junction with the duodenum. This is also known as a choledochocoele.
Type IV: Secondarily to type I, type IV is the next common manifestation of a choledochal cyst. Subtypes include:
Type V: otherwise known as Caroli disease. Multiple distentions appear on the intrahepatic ducts.
A theory suggests that choledochal cysts are formed due to malformations in the pancreatobiliary junction or the sphincter of Oddi. These malformations lead to the reflux of fluids from the duodenum to the biliary tree, which is not accustomed to their presence; therefore, it becomes distended. Choledochal cysts are diagnosed non-invasively most of the times, with the help of an ultrasonographic scan, a computerized tomography (CT) scan or a magnetic resonance imaging (MRI) scan. Should these modalities fail to produce a trustworthy, accurate diagnosis, invasive techniques may also be used with caution, such as endoscopic retrograde cholangiopancreatography (ERCP). Choledochal cysts are surgically treated and prognosis is remarkable, given that serious comorbidities do not exist.
The bile ducts are channels that begin from the inner part of the liver and follow a route to the duodenum, a part of the small intestine. They are responsible for carrying bile, a fluid produced in the liver, to the small intestine, so as for digestion to take place.
Choledochal cysts are parts of the bile duct that are distended, like a pouch. A person is born with this abnormality and the causes are unknown.
Typical symptoms involve occasional pain and/or swelling in the abdomen, a yellow skin color (jaundice), peritonitis or cholangitis. Cysts are diagnosed most frequently with an ultrasound scan, but a CT/MRI scan, as well as blood tests. In more difficult-to-diagnose cases, an MRCP (magnetic resonance cholangio-pancreatography) or ERCP (endoscopic retrograde cholangio-pancreatography) may be performed. The treatment of choice is a complete surgical removal of the cyst, since other methods have not proven beneficial for the patients on the long term. Patients who have Caroli disease, a sub-category of choledochal cysts found within the liver, will need to have a part of their liver removed. Any individual who presents with cholangitis, i.e a critical bacterial inflammation of the biliary tree, is necessarily treated with antimicrobials prior to any type of surgical intervention.
Another category of patients, who do not usually receive surgical treatment, is patients who are diagnosed at a progressed stage of the condition, when liver cirrhosis or portal hypertension have already manifested. These patients run a higher risk of complications or death and are therefore not treated surgically as a rule.