Choledochal cyst is a congenital anomaly involving cystic dilation of the bile ducts. It is classified into 5 types based on the location and extent of dilation. Type I is the most common. Imaging plays an important role in diagnosis and classification, with MRCP being the gold standard. Treatment involves complete excision of the cyst and Roux-en-Y hepaticojejunostomy. Complications include stones, malignancy, cholangitis and rupture. Caroli's disease is a rare disorder involving saccular dilation of intrahepatic bile ducts.
4. Epidemiology
• Incidence
• Western population-
1 in 100,000 to 150000 live births
• More common in Asia
• 1 in 1000 live births in Japan
• Sex prevalence
Female dominance-
• 3-4:1
5. Biliary tree anatomy
Intrahepatic
Ductular and canalicular network of the acini
Interlobular ducts
Septal bile ducts
RHD & LHD
Extrahepatic
RHD & LHD
CHD
Cystic duct & GB
CBD
6. Normal size of bile ducts
• CBD
• Adolescents & adults
• Upto 8mm
• Post cholecystectomy
• Upto 12 mm
• >60 years of age
• +1mm per decade
• Cystic duct
• Upto 1.8 mm
CHD at porta hepatis-
5 mm
8. Types
• I a- dilation of extrahepatic bile duct (entire)
• Ib- dilation of of extrahepatic bile duct (focal)
• Ic- dilation of CBD portion of extrahepatic bile duct
• II- diverticulum of the CBD
• III- cystic dilation of the distal intraduodenal CBD
• IVa-multiple cysts intrahepatically & extrahepatically
• IVb- multiple cysts extrahepatically
• V- single or multiple intrahepatic cysts without extrahepatic
duct dilation.
9. 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr
Type IV
Type V
Occurrence
Type I – 61 %
Type II – less common
Type III – less common
Type IV - 28.5 %
Type V – 4.6%.
Type I
Type II
& III
10. Types of union between CBD+MPD
• Normal junction (union inside duodenal
wall)
1) 2-10 mm short common channel with a
diameter of 3-5 mm(55-85%)
2) Separate entrances into
duodenum(42%)
3) 8-15 mm long common channel
• Abnormal junction (union outside
duodenal wall)
1) MPD inserting into CBD >15 MM
from entrance into duodenum
2) CBD entering into MPD
11. Etiology
• Weakness of the duct wall
• Pancreaticobiliary maljunction / Long common channel
o Proximal insertion of MPD into CBD or vice versa outside duodenal
wall producing
a long common channel (>15 mm)
o Reflux of pancreatic enzymes into CBD that causes damage to the
ductal wall and leads to cyst formation
12. Clinical presentation
• Triad of –
• Abdominal pain
• Jaundice
• Right upper quadrant palpable mass
Infantile form
• Present before 12 months of age
• Present with obstructive jaundice, acholic stools & hepatomegaly
• Signs of hepatic fibrosis may be present
Adult form
• Anytime after 12 months of age
• May present with fever, nausea, vomiting & jaundice.
• Undiagnosed cases may present with cholelithiasis.
14. Histopathology
• Ducts are thickened (connective tissue+smooth muscle strands)
• Inflammatory reaction increases with age, may lead to ulceration in
mucosa & submucosa
• May lack a typical biliary mucosal lining
• Repeated destruction and regrowth causes epithelial metaplasia
• High risk of adenocarcinoma
16. Objectives of imaging
• To classify
• Mention extension
• To visualize pancreaticobiliary junction
• To rule out association with other diseases
• To search for associated complications
• To rule out differentials
17. USG
• Ballooned/fusiform cyst beneath porta hepatis separate from GB
• *Communication with bile duct needs to be demonstrated*
• Abrupt change of caliber at junction of dilated segment to normal
ducts
• Intrahepatic bile duct dilatation secondary to stenosis.
18.
19.
20.
21. CT Scan
• Useful in identifying type IV & type V disease
• CT Cholangiography
• More sensitive for visualizing biliary tree
• More sensitive in detecting choledochal cysts
• Less sensitive to characterize pancreatic duct
22.
23.
24. MRI
• T1WI : hypointense dilatation of bile duct
• T2WI : hyperintense
28. MRCP
• Gold standard for imaging choledochal cyst
• Administration of secretin increases pancreatic secretion and dilates
the pancreatic duct
29.
30. Type II ( diverticulum) choledochal cyst arising from lateral wall of CBD
31. ERCP
• More useful in type III choledochal cyst to exclude periampullary
mass
Fusiform choledochal cyst with a long common channel
& stricture at pancreatico biliary junction
33. HIDA Scan
• The normal scan provides functional & morphological information
about the hepatic parenchyma in the first 10min ( after inj. of
radionuclide), extrahepatic biliary tree by 20 min and excretion into
the bowel by 1 hour.
• Useful in demonstrating biliary peritonitis after choledochal cyst
rupture
36. Caroli’s disease / Type V Choledochal cyst
• Rare congenital disease
• Autosomal recessive disorder
• Characterized by multifocal segmental saccular cystic dilatation of the
large intrahepatic bile ducts, which retain their communication with
the biliary tree
• May be diffuse / segmental / lobar
48. Treatment
• Type I & IV
• Cyst excision & hepaticojejunostomy to a Roux-en-Y limb
• Type II
• Simple cyst resection
• Type III
• Marsupialization of the cyst ,
usually through transduodenal approach
• Type V
• Segmental resection of liver if disease is localized
• Liver transplantation
49. Complications
• Stones in GB, CBD, within cyst, in MPD, in intrahepatic biliary tree
• Malignant transformation
• Recurrent pancreatitis
• Cholangitis/Cholecystitis
• Cyst rupture with bile peritonitis
• Bleeding
• Biliary cirrhosis + portal hypertension
• Portal vein thrombosis
• Hepatic abscess
50. References
• Textbook of Radiology & Imaging - David Sutton 7th Edition
• Diagnostic Ultrasound - Carol M. Rumack 4th Edition
• Radiology Review Manual - Wolfgang Dahnert 7th Edition
• Bailey & Love’s Short Practice of Surgery - 7th Edition
• Paediatric Surgery - Arnold G. Coran - 7th Edition