What cyst is this?

Case Report

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 reserved.

Questions

1. Describe the abnormality seen?
2. What is the most likely diagnosis? What is the classification for this condition and how do they present clinically?
3. What are the other differential diagnoses?
4. How would you confirm the diagnosis?
5. What are the possible complications?
6. How are these lesions treated?

Answers

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 [1] 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 [2]

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) [3].

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 [1] 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 [2] 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 [6]. 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 [7] 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 [8].

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 cholestatic jaundice.

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” [9]. 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 [2].

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 [1]. In addition, ERCP also provides the opportunity for therapeutic sphincterotomy or incision of the choledochocoele.

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 [10]. 

Recently, dynamic MRCP with secretin stimulation has been shown to be an effective diagnostic technique [11].  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 [2]. 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 chronic pancreatitis.

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 [1]. 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 carcinoma [2].

6. How are these lesions treated?

The gold standard treatment for choledocal cysts is total cyst excision and cholecystectomy [4]. 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 was normal.

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 [12]. 

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.

Pearls

• 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 alcoholic disease.
• 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 demonstrating choledochocoele.
• In selected cases choledochocoele may be treated effectively by endoscopic sphincterotomy

[View this Figure]

Figure 1 Axial and coronal reformatted contrast enhanced CT at the level of the pancreas.

[View this Figure]

Figure 1A Axial and coronal reformatted contrast enhanced CT at the level of the pancreas.

[View this Figure]

Figure 2 Greene’s Classification of Choledochocoele [5]. 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 [3].

[View this Figure]

Figure 3 Axial contrast enhanced CT abdomen. Arrows showing a membrane-like residual lesion at the site of the previous choledochocoele.

References

1. Todani T, Watanabe Y, Narusue M et al. Congenital bile duct cysts: Classification, operative procedures, and review of thirty-seven cases including cancer arising from choledochal cyst. Am J Surg 1977; 134(2):263-9.   [Medline]
   
2. Huycke A, Moeller DD. Hepatic portal venous gas after colonoscopy in granulomatous colitis. Am J Gastroenterol 1985; 80(8):637-8.   [Medline]
   
3. Greene FL, Brown JJ, Rubinstein P et al. Choledochocele and recurrent pancreatitis. Diagnosis and surgical management. Am J Surg 1985; 149(2):306-9.   [Medline]
   
4. Liu CL, Fan ST, Lo CM et al. Choledochal cysts in adults. Arch Surg 2002; 137(4):465-8.   [Medline]
   
5. Todani T, Watanabe Y, Toki A et al. Carcinoma related to choledochal cysts with internal drainage operations. Surg Gynecol Obstet 1987; 164(1):61-4.   [Medline]
   
6. Todani T, Watanabe Y, Fujii T et al. Anomalous arrangement of the pancreatobiliary ductal system in patients with a choledochal cyst. Am J Surg 1984; 147(5):672-6.   [Medline]
   
7. Iwai N, Tokiwa K, Tsuto T et al. Biliary manometry in choledochal cyst with abnormal choledochopancreatico ductal junction. J Pediatr Surg 1986; 21(10):873-6.   [Medline]
   
8. Voyles CR, Smadja C, Shands WC et al. Carcinoma in choledochal cysts. Age-related incidence. Arch Surg 1983; 118(8):986-8.   [Medline]
   
9. Arenas-Jimenez JJ, Gomez-Fernandez-Montes J, Mas-Estelles F et al. Large choledochocoele: difficulties in radiological diagnosis. Pediatr Radiol 1999; 29(11):807-10.   [Medline]
   
10. Ito K, Koike S, Matsunaga N. MR imaging of pancreatic diseases. Eur J Radiol 2001; 38(2):78-93.   [Medline]
    
11. Hellerhoff KJ, Helmberger H 3rd, Rosch T et al. Dynamic MR pancreatography after secretin administration: image quality and diagnostic accuracy. AJR Am J Roentgenol 2002; 179(1):121-9.   [Medline]
    
12. Hopkins NF, Benjamin IS, Thompson MH et al. Complications of choledochal cysts in adulthood. Ann R Coll Surg Engl 1990; 72(4):229-35.   [Medline]
    

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