What cyst is this?
1 Department of Biomedical Imaging, Faculty of
Medicine, University of Malaya, Kuala Lumpur, Malaysia
2 Department of Surgery, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
A forty-year-old woman presented with recurrent epigastric
pain for 6 months. The pain was increasing both in frequency and severity.
Further questioning revealed that she has had similar episodes of abdominal
pain since childhood, for which she was treated symptomatically with antacids.
This gave her temporary relief. On the first admission she had acute pancreatitis
with elevated serum amylase levels (959 IU/ml). She was treated conservatively
and recovered well. Ultrasound at that time was normal. On follow-up, the
abdominal pain had increased in severity and a CT scan was performed (Figure
1). � 2007 Biomedical Imaging and Intervention Journal. All rights
- Describe the abnormality seen?
- What is the most likely diagnosis? What is the classification for this
condition and how do they present clinically?
- What are the other differential diagnoses?
- How would you confirm the diagnosis?
- What are the possible complications?
- How are these lesions treated?
1. Describe the abnormality seen?
Axial contrast enhanced CT scan of the abdomen shows a
round, well-defined hypo-dense filling defect (1.9 cm X 4.5 cm) seen in the
distended second part of duodenum (D2) (arrow) (Figure 1A).� CT value of
this mass is 8- 10 HU. This lesion appears closely related to the medial wall
of D2 but is separate from its lateral walls. The proximal common bile duct is
normal in caliber. The pancreas is normal. Pancreatic duct is not dilated.
There is no evidence of acute pancreatitis. Liver, intrahepatic ducts and
gallbladder is normal.
2. What is the most likely diagnosis? What is the classification and how do
they present clinically?
In the case presented, based on the CT appearance, the
most likely diagnosis is a choledochocoele type IIIa. This would explain the
appearance of a filling defect in the second part of duodenum in the axial CT
scan.� Furthermore the choledochocoele was sizeable enough to obscure the
papilla on ERCP. Following the incision of the cyst and drainage of its fluid
content, the papilla was seen and cannulated. The papilla appeared normal and
injection of contrast delineated normal common bile duct, pancreatic duct,
gallbladder and intrahepatic ducts. The terminal portion of the common bile
duct and pancreatic duct emptied into a common channel.
Biliary duct cysts are various anatomic forms of biliary
cystic dilatations occurring in any part of the bile duct between the liver and
the duodenum. The classification of Todani et al which is an expansion of the
Aloson-Lejs classification  is most often used
- Type� I: Commonest type� 80-90%
- (Ia)� Choledochal cyst in the narrow sense
- (Ib)� Segmental choledochal dilatation
- (Ic)� Diffuse or cylindrical dilatation
- Type� II: Diverticulum anywhere in the extrahepatic duct�� 2%
- Type III: Choledochocoele involving the intraduodenal portion of the
common bile duct�� 1.4-5%
- Type IVA: Multiple intrahepatic and extrhepatic cysts�� 19%
- Type IVB: Multiple extrahepatic cysts
- Type V: Single or multiple intrahepatic cysts� or Caroli�s disease 
Choledochocoele can be further subdivided into three
subtypes; Type IIIa represents the choledochocoele in the intraluminal duodenum
and contains the terminal pancreatic and common bile duct as a common channel;
Type IIIb contains separate ductal structures with an intraluminal cyst and
Type IIIc shows a cyst completely contained within the intramural portion of the
duodenum (Figure 2) .
The estimated incidence of choledocal cysts is 1 in 13,000
to 1 in 2 million live births being four times more common in females and is
more common in Asians  The risk is age-related, with children below the age
of 10 years having low risk and the risk increasing after the age of 20 years [4,5].
Some authors have proposed that choledochoceles are congenital in origin 
while others suggest abnormal biliary motility could be a contributing factor
in the pathogenesis of choledochoceles. The size of choledochoceles, vary from
a few millimeters to a few centimeters.
An abnormal pancreaticobiliary junction, characterized as
a long common channel, is present in about 70% of patients with choledochal
cysts. The pancreaticobiliary junction which lies outside the Oddi's sphincter
may increase the likelihood of pancreatic juice reflux into the biliary tree . Clinical findings corresponding to higher pressure in the
pancreatic duct than in the CBD and high amylase concentrations in the bile are
generally accepted as suggesting pancreaticobiliary reflux 
therefore both pancreaticobiliary reflux and stasis of a mixed fluid of bile
and pancreatic juice are major factors in the pathophysiology of inflammation
and carcinogenesis .
Clinical manifestations of choledocal cyst are age
dependent. Since biliary tree inflammation is common in older patients, they
may present with intermittent biliary colic, recurrent pancreatitis or
3. What are the other differential diagnoses?
The differential diagnosis includes intraluminal duodenal
diverticulum and duodenal duplication cyst communicating with the biliary tree.
A duodenal diverticulum would become filled with oral contrast media while the
others will not. Histologically choledochocoele should demonstrate biliary mucosa on its inner sides, while duodenal duplication cysts are internally covered with duodenal mucosa which may include the presence of a muscular lining with or without ectopic gastric or pancreatic tissue.
Duodenal duplication cysts communicating with the biliary
tree cannot be differentiated from choledochocoele by endoscopy. On gross
pathology they both appear identical.� Both fill with biliary contrast media as
they communicate with the duodenum on one side and the ampulla on the other.
Both appear as a filling defect in upper gastrointestinal series. Therefore it
has been suggested that choledochocoeles and duodenal duplication cysyts
communicating with the biliary tree are congenital periampullary lesions in
direct communication with the biliary tree. Since both present with the same
clinical picture and are identical from a radiological point of view, they
could be referred to as �cystic periampullary malformative disorders� .
Biopsy of the cyst wall demonstrated intestinal mucosa as the choledochocoele
represents a prolapse or herniation of the intramural segment of the distal
common bile duct into the duodenal lumen and may be lined by duodenal mucosa .
4. How would you confirm the diagnosis?
The most reliable diagnostic technique is ERCP since
choledochocoeles are often associated with structural alteration of the papilla
of Vater and the periampullary region, which can be directly visualized on ERCP
as well as opacification of the CBD and pancreatic ducts . In addition, ERCP
also provides the opportunity for therapeutic sphincterotomy or incision of the
Magnetic Resonance Cholangiopancreatography (MRCP) has a
diagnostic accuracy of 75% in cases of pancreaticobiliary maljunction, where
the diagnostic findings include an anomalous union between the common bile duct
and the pancreatic duct as well as a long common channel. The length of the
common channel varies periodically as this is based on the spasms of the
sphincter muscle of Oddi. Unlike ERCP, conventional MRCP is a static
examination and the length of the common channel measured tends to be shorter
than on ERCP .�
Recently, dynamic MRCP with secretin stimulation has been
shown to be an effective diagnostic technique . �Secretin stimulates the
exocrine pancreas to secrete fluid and bicarbonate. This fluid improves the
delineation of the pancreatic duct. However MRCP potentially has poor
definition of the pancreatic duct branch and peripheral biliary tree, as well
as the inherent poor spatial resolution compared to ERCP.
Choledochoceles especially if they are small, may cause
little deformities of the duodenal mucosa and can be easily overlooked by
conventional diagnostic methods such as ultrasound, upper gastrointestinal series
and CT especially if the second part of duodenum is not filled with oral
contrast . CT may be helpful in demonstrating a cystic filling defect in the
periampullary region. CT is also able to demonstrate the relationship between
the choledochocele and the CBD and pancreatic duct and the presence of acute or
5. What are the possible complications?
Complications of biliary duct cysts include recurrent
pancreatitis, pancreatic necrosis, cholangitis, primary cyst stones and carcinoma.
The risk of developing cancer is related to bile stasis and contact of the
epithelium with bile . The overall risk of developing a malignancy in bile
duct cysts is estimated at 2.5%. The histological types of cancer reported vary
from adenocarcinoma, squamous cell carcinoma and undifferentiated bile duct
6. How are these lesions treated?
The gold standard treatment for choledocal cysts is total
cyst excision and cholecystectomy . Associated malignancy warrants more
extensive surgery such as Whipple�s operation for lower common bile duct cancer
or hepatectomy for proximal bile duct cancer or gallbladder cancer. Roux-en-Y
hepaticojejunostomy or, less commonly, hepaticoduodenostomy is indicated to
restore biliary drainage. For patients with symptoms of pain and jaundice,
effective drainage of the common bile duct and pancreatic duct can be achieved
by endoscopic sphincterotomy or operative laporotomy. For long-term prophylaxis
and to treat cholangitis, antibiotics are helpful.
In this patient, the cystic lesion was incised and clear
fluid with a whitish substance was drained completely. The papilla was then
seen and cannulated. Common bile duct (CBD), pancreatic duct and gallbladder
appeared normal. Biopsy of the cyst epithelium revealed the presence of only
intestinal mucosa without a smooth muscle layer. No evidence of malignancy was
detected. The patient�s symptoms improved and a repeat ERCP four weeks later
Internal or external drainage of a choledocal cyst by
choledochocystojejunostomy or T-tube choledochocystomy is associated with
complications such as suppurative cholangitis, lithiasis, pancreatitis,
secondary biliary cirrhosis, portal hypertension, and intrahepatic abscess. New
technical advances in diagnostic and therapeutic procedures and increased
surgical experience have lowered the mortality rate. Roux-en-Y
choledochojejunostomy is the preferred operative procedure .�
The patient remained asymptomatic for 6 months before her
symptoms recurred. A repeat CT scan (Figure 3) demonstrated residual membrane
like substances at the site of the previously noted cyst.� She was treated
symptomatically and had temporary relief. Magnetic resonance
cholangiopancreatography performed one year later showed persistence of the
membranes of the cyst in D2. The intrahepatic bile ducts, pancreatic ducts and
proximal CBD appeared normal.
- Diagnosis of choledochocoele should be included in the differential
diagnosis of patients who present with recurrent abdominal pain and pancreatitis
without the usual historical or diagnostic findings of biliary tract or
- Detection of a choledochocoele is important as it may be overlooked by
diagnostic methods such as ultrasound and upper gastrointestinal series
- A choledochocoele is a rare abnormality involving the intramural portion
of the distal common bile duct within the duodenal wall
- Endoscopic retrograde cholangiopancreatography is helpful in
- In selected cases choledochocoele may be treated effectively by
Figure 1 Axial and coronal reformatted contrast enhanced CT at the level of the pancreas.
Figure 1A Axial and coronal reformatted contrast enhanced CT at the level of the pancreas.
Figure 2 Greene�s Classification of Choledochocoele . IIIa Large intraluminal choledochocoele with common openings for CBD and pancreatic duct; IIIb Large intraluminal choledochocoele with separate openings for CBD and pancreatic duct and IIIc Intraluminal choledochocele. Reprinted with permission from .
Figure 3 Axial contrast enhanced CT abdomen. Arrows showing a membrane-like residual lesion at the site of the previous choledochocoele.
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|Received 15 January 2007; received in revised form 11 February 2007; accepted 3 April 2007
Correspondence: Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia. Tel.: 603 79492069; Fax: 603 79581973; E-mail: firstname.lastname@example.org (Basri J.J. Abdullah).
Please cite as: Harun SM, Abdullah BJJ, Rajasingam V,
What cyst is this?, Biomed Imaging Interv J 2007; 3(4):e44
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