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ABDOMINAL IMAGING Table of Contents   
Year : 2002  |  Volume : 12  |  Issue : 2  |  Page : 225-228
Images : Choledochal cyst


Depts of Radiodiagnosis & Surgery Command Hospital (SC), Pune 411040, India

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Keywords: Choledochal Cyst, bile duct, cholangiography

How to cite this article:
Singh H, Khanna V, Puri B, Maurya V, Sivasankar R. Images : Choledochal cyst. Indian J Radiol Imaging 2002;12:225-8

How to cite this URL:
Singh H, Khanna V, Puri B, Maurya V, Sivasankar R. Images : Choledochal cyst. Indian J Radiol Imaging [serial online] 2002 [cited 2014 Oct 24];12:225-8. Available from: http://www.ijri.org/text.asp?2002/12/2/225/28451
Choledochal Cyst is the cystic dilatation of the extrahepatic bile ducts, with or without dilatation of the intrahepatic ducts. It is a common congenital anomaly of the biliary tree. It is 3 to 4 times more common in females and two thirds of the patients remain asymptomatic before the age of 10 years [1]. The classic clinical triad of pain, jaundice and a palpable right upper quadrant lump is seen in 30-60% of patients presenting in the first decade of life and approximately 20% of those diagnosed in adulthood [1],[2].


   Case Report Top


9-year-old female child presented with history of fever, jaundice, pain and lump in the right hypochondrium of 15 days duration. On examination the liver was palpable 4 cm below the right costal margin. Biochemical investigations revealed Hb 7.8 gm%, TLC 9100/mm3, PCV 37%, ALT 68 IU, AST 39 IU, serum bilirubin 2.6 mg%, alkaline phosphatase was raised. Total proteins were 6.6 gm% (A:G 1:1.1). PT and PTTK were mildly deranged. Ultrasonography of the abdomen showed a 9.2 x 6.7 x 5.6 cm well defined cystic lesion with echogenic layered debris in the subhepatic region posteromedial to the gall bladder and communicating with the cystic duct [Figure - 1],[Figure - 2]. The left hepatic duct was grossly dilated and ectatic [Figure - 3] with external compression of the portal vein and the common bile duct was not identified separately from this cystic lesion suggesting the diagnosis of choledochal cyst. Axial CT scan abdomen revealed a cystic lesion (12-20 HU) in the right lobe of the liver medial to the gall bladder [Figure - 4]. There was dilatation and ectasia of the left hepatic duct [Figure - 5]. MR Cholangiography confirmed the diagnosis of choledochal cyst [Figure - 6],[Figure - 7] and it was graded as type IVB according to Todani's classification. Preoperatively there was cystic dilatation of the common bile duct with dilatation and ectasia of the left hepatic duct. The cyst was completely excised [Figure - 8],[Figure - 9] and biliary enteric anastomosis was done. Postoperative period was uneventful


   Discussion Top


The origin of these cysts is uncertain. The most likely etiology is bile duct injury resulting from sequelae of an anomalous junction of the pancreatic duct and the distal common bile duct (CBD) [3]. This anomalous junction results in chronic reflux of pancreatic enzymes into the biliary tree with resultant weakening, scarring and dilatation of the CBD wall. Anomalous junction is found in 10-58% of cases with choledochal cysts [1].

The original classification of Alonzo-Lej has been modified by Todani et al [4] who described five types of choledochal cysts. Type I choledochal cysts accounting for 80-90% of bile duct cysts. They are further subdivided into A, B and C subtypes. Type I A is cystic dilatation of the CBD, type I B is focal, segmental dilatation of the distal CBD and type I C is fusiform dilatation of both the common hepatic and common bile duct. Type II cysts account for 2% of bile duct cysts and are true diverticulae arising from the CBD. Type III cysts are defined as cystic dilatation involving only the intraduodenal portion of the CBD and are called choledochocele accounting for 1 to 5% of bile duct cysts. Type IV cysts account for approximately 10% of bile duct cysts and are subdivided into types IV A and IV B. Type IV A has multiple intra and extrahepatic cysts and type IV B has multiple extrahepatic cysts only. Type V cysts comprise the remainder of bile duct cysts. Generally this type involves only the intrahepatic ducts and may be single or multiple. When multiple the condition is termed as Caroli's disease [1],[5].

Complications associated with choledochal cyst include cholelithiasis, choledocholithiasis, cystolithiasis, ascending cholangitis, bile duct strictures, intrahepatic abscesses, biliary cirrhosis, portal hypertension and hepatobiliary malignancy. Tumors occur in the intra and extrahepatic ducts, both intra and extracystic in position. Patients are also at increased risk of gall bladder carcinoma.

The role of imaging in the evaluation of choledochal cyst is to delineate the anatomy of the cyst, determine the relationship of the cyst to the rest of the intra and extrahepatic biliary tree, evaluate associated complications and biliary tree abnormalities. Sonography is useful in assessing the full extent of biliary duct dilatation and for identifying the communication between the cyst and the biliary tree as seen in this case. It can also demonstrate the presence of calculi, stricture or tumor if present.

On CT and MRI, a choledochal cyst appears as a right upper quadrant, fluid filled structure in contiguity with the extrahepatic bile duct. Coronal imaging is extremely useful in the demonstration of the communication between the cyst and the biliary tree. This is achievable by CT using multiplanar reformations with or without cholangiographic contrast agents. MR Cholangiographic technique allows direct imaging of the cyst in multiple planes [6,7]. Coronal imaging reveals a dilated tubular structure that follows the expected course of the CBD and demonstrates the relationship of the cyst with the rest of the biliary tree. The presence of wall thickening, mural nodularity and wall enhancement in a choledochal cyst raises the possibility of tumor. Direct cholangiographic techniques such as PTC and ERCP are the most reliable methods to completely evaluate the biliary tree and the presence of an anomalous junction of the pancreatic duct and the CBD. Once a choledochal cyst is detected at sonography, MR cholangiography should be performed prior to surgery.

The treatment for types I, II and IV choledochal cysts is complete excision with biliary-enteric anastomosis for drainage. The type III cysts are treated by deroofing of the cyst since they do not carry an increased risk of hepato-biliary malignancy [8].

The large choledochal cysts can be confused with large intrahepatic cystic lesions such as hydatid cyst on axial CT imaging alone. However the Ultrasound evaluation is mandatory in such cases which can easily show the relation of the cyst to the liver and show communication with other extrahepatic biliary ducts as seen in this case.

 
   References Top

1.Savader SJ, Beneati JF, Venbrux AC et al . Choledochal cysts: classification and cholangiographic appearance. AJR 1991;156:327-331.   Back to cited text no. 1    
2.Montana MA, Rohrmann CA. Cholangiocarcinoma in choledochal cyst: preoperative diagnosis. AJR 1986;147:516-517.  Back to cited text no. 2  [PUBMED]  
3.Babbit DP. Congenital choledochal cyst: new etiological concept based on anomalous relationships of common bile duct and pancreatic bulb. Ann Radiol (Paris) 1969;12:231-240.  Back to cited text no. 3    
4.Todani T, Watanabe Y, Narusue M et al . Congenital bile duct cysts: classification, operative procedure and review of thirty seven cases including cancer arising from choledochal cyst. Am J Surg 1977;134:263-269.  Back to cited text no. 4    
5.Cory DA, Don S, West KW. CT cholangiography of a choledochocoele. Paediatric Radiology 1990;21:73-74.  Back to cited text no. 5  [PUBMED]  
6.Lam WW, LamTP, Saing H, Chan FL, Chan KL. MR cholangiography and CT cholangiography of pediatric patients with choledochal cysts. AJR 1999;173:401-405.  Back to cited text no. 6    
7.Irie H, Honda H, Jimi M et al . Value of MR cholangiopancreatography in evaluating choledochal cysts. AJR 1998;171:1381-1385.  Back to cited text no. 7    
8.Venu RP, Greenen JE. Periampullary region: physiology and pathophysiology.In: Silvis SE, Rohrmann CA, Ansel HJ eds. Text and atlas of endoscopicretrograde cholangiopancreatography. New York: Igaku-Shoin 1995;146-167  Back to cited text no. 8    

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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9]



 

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