Diagnostic Ultrasound - Abdomen and Pelvis

Choledochal Cyst
Diagnoses: Biliary System
PATHOLOGY
General Features
• Etiology
○ 2 main hypotheses
– Congenital ductal plate malformation
– APBDU proximal to duodenal papilla forming long
common channel, strongly associated with type I and
IV
□ Higher pressure in pancreatic duct and absent
ductal sphincter
□ Free reflux of pancreatic enzymes into CBD causes
weakening of CBD wall and dilatation
○ Additional theories
– Decrease in number of ganglion cells in narrow
portion of bile duct causes increased intraluminal
pressure, reovirus infection, failure of recanalization,
familial pattern of inheritance, or duodenal
duplication
• Associated abnormalities
○ Gallbladder: Aplasia or double gallbladder
○ Biliary anomalies
– Biliary atresia or stenosis
– Other forms of fibropolycystic disease (congenital
hepatic fibrosis, biliary hamartomas)
○ Annular pancreas
Staging, Grading, & Classification
• Classification of choledochal cyst: Todani classification
• Classification of APBDU: Komi classification
○ Type P-B: Perpendicular insertion of pancreatic duct into
CBD (acute-angled union, fusiform dilatation)
○ Type B-P: Perpendicular insertion of CBD into pancreatic
duct (right-angled union, cystic dilatation)
○ 2 major duct unions are associated with type I
choledochal cyst
Gross Pathologic & Surgical Features
• Cystic/fusiform dilated sac with bile, stones, or sludge
• Cyst wall is thickened, fibrotic, and occasionally calcified in
adults
• Long ectatic common channel with pancreatic duct (normal
length: 0.2-1.0 cm)
Microscopic Features
• Thickened ductal wall consists of chronic inflammation and
fibrosis
• Widespread ulceration and denuded mucosa in dilated CBD
• Biliary epithelium lining the cyst is often intact in infants
• Goblet cell metaplasia and epithelial dysplasia may play role
in subsequent development of carcinoma
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Triad: Recurrent RUQ pain, jaundice, palpable mass
○ Infant: Intermittent jaundice, acholic stools,
hepatomegaly, palpable abdominal mass
○ Children and adult: Upper abdominal pain, jaundice,
recurrent cholangitis/pancreatitis
Demographics
• Age
○ Usually diagnosed in infancy and childhood
○ 25% detected before age 1; 80% diagnosed in childhood
(60% before age 10); 20% in adults
• Gender
○ M:F = 1:3-4 (more common in females)
• Epidemiology
○ Prevalence: 1:13,000 admissions
○ More common in Asians
Natural History & Prognosis
• Low-grade biliary obstruction may develop and can
potentially result in cirrhosis and portal hypertension
• Prevalence of adenocarcinoma arising in choledochal cysts
○ Varies from 2-18%,corresponding to roughly 5-35x
increased risk
• Other complications:Biliary calculi, cholangitis, pancreatitis
• Prognosis: Usually good after surgical repair, but poor if
malignant degeneration occurs
Treatment
• Type I: Complete surgical excision + Roux-en-Y
choledochojejunostomy
• Type II: Cysts can usually be surgically excised entirely
• Type III: Choledochocele < 3 cm: Endoscopic
sphincterotomy; > 3 cm: Surgically excised via
transduodenal approach
• Type IV: Dilatated extrahepatic duct completely excised
with biliary-enteric drainage procedure, intrahepatic
involvement left untreated
• Type V: If limited to single hepatic lobe, may be resected;
diffuse disease + liver failure: Liver transplantation
DIAGNOSTIC CHECKLIST
Consider
• Rule out other causes of marked biliary dilatation
Image Interpretation Pearls
• MRCP or ERCP: Cystic or fusiform dilatation of bile ducts
without obstructive lesion
SELECTED REFERENCES
1. Venkatanarasimha N et al: Imaging features of ductal plate malformations in
adults. Clin Radiol. 66(11):1086-93, 2011
2. Lee HK et al: Imaging features of adult choledochal cysts: a pictorial review.
Korean J Radiol. 10(1):71-80, 2009
3. Mortele KJ et al: Multimodality imaging of pancreatic and biliary congenital
anomalies. Radiographics 26: 715-731; 2006
4. Sugiyama M et al: Anomalous pancreaticobiliary junction shown on
multidetector CT. AJR Am J Roentgenol. 180(1):173-5, 2003
5. Todani T et al: Classification of congenital biliary cystic disease: special
reference to type Ic and IVA cysts with primary ductal stricture. J
Hepatobiliary Pancreat Surg. 10(5):340-4, 2003
6. Benya EC: Pancreas and biliary system: imaging of developmental anomalies
and diseases unique to children. Radiol Clin North Am. 40(6):1355-62, 2002
7. de Vries JS et al: Choledochal cysts: age of presentation, symptoms, and late
complications related to Todani's classification. J Pediatr Surg. 37(11):1568-
73, 2002
8. Krause D et al: MRI for evaluating congenital bile duct abnormalities. J
Comput Assist Tomogr. 26(4):541-52, 2002
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