What is not typically true for choledochal cysts, which are congenital (present at birth) cystic dilations of the intrahepatic and/or extrahepatic biliary tree (bile ducts)?

Characteristics of Choledochal Cysts

The incorrect statement about choledochal cysts is that the incidence is 1:1,000 (option A), as the actual prevalence varies from 1:100,000 in Western countries to 1:13,000 in Japan. 1, 2

Epidemiology of Choledochal Cysts

• Choledochal cysts have a reported prevalence ranging from 1:100,000 in Western populations to significantly higher rates (1:13,000) in Asian countries, particularly Japan 1, 2
• They occur 3-8 times more frequently in females than males, making option C (3-8x more common in females than males) a correct statement 3
• The condition is considered rare in Western countries, which contributes to potential diagnostic delays 3

Pathophysiology and Definition

• Choledochal cysts are indeed congenital cystic dilations of the intrahepatic and/or extrahepatic biliary tree, making option D a correct statement 1, 4
• Over 90% of patients with choledochal cysts have an anomalous pancreaticobiliary duct junction, with the pancreatic duct joining the common bile duct >1 cm proximal to the ampulla, confirming option B as correct 3
• This anomalous junction allows pancreatic enzymes to reflux into the biliary system, contributing to inflammation, biliary epithelial damage, and increased risk of malignancy 3

Clinical Significance and Management

• Choledochal cysts are associated with a significantly increased risk of developing cholangiocarcinoma if left untreated 4
• The risk of malignant transformation (cholangiocarcinoma) is reported to be up to 30% in untreated cases 2
• Complete excision of the choledochal cyst with Roux-en-Y hepaticojejunostomy is the treatment of choice to prevent malignant transformation 1, 4
• Cases registered with the Japanese Study Group on Pancreaticobiliary Maljunction over a 10-year period indicated that the incidence of cholangiocarcinoma is 7.0% in cases of pancreaticobiliary maljunction with dilated bile ducts (choledochal cysts) 3

Classification and Types

• Choledochal cysts are categorized according to the Todani classification based on location, shape, and multiplicity 1, 2
• Type I (solitary, extrahepatic) and Type IV (intra- plus extrahepatic) bile duct cysts have the greatest predisposition to malignancy 1

Clinical Presentation and Diagnosis

• Patients may present with jaundice (84-90%), weight loss (35%), abdominal pain (30%), nausea and vomiting (12-25%), and fever (10%) 3, 1
• Many patients are asymptomatic and diagnosed incidentally 1
• Contrast-enhanced MRI with magnetic resonance cholangiopancreatography (MRCP) is superior for accurate assessment of biliary obstruction 1