CHOLEDOCHAL CYST – A CASE REPORT PRESENTING AUTHOR – DR.K.PRASANNA POST GRADUATE STUDENT, RAJAH MUTHIAH MEDICAL COLLEGE & HOSPITAL (RMMCH), ANNAMALAI UNIVERSITY, CHIDAMBARAM

CLINICAL HISTORY 14 year old boy Came with complaints of right hypochondrial pain for the past two days Associated with fever and vomiting. There is no history of trauma. On clinical examination there is no evidence of jaundice Right hypochondrial tenderness present. Clinically diagnosis of liver abscess was made and was referred to radiology department.

USG ABDOMEN Ultrasonography of abdomen showed a 9.2 x 6.7 x 5.6 cm well defined cystic lesion with minimal echogenic layered debris postero medial to the gall bladder No evidence of any colour flow within the cystic lesion communication with the cystic duct cannot be clearly made out. Other abdominal organs appears normal Cystic lesion

CT ABDOMEN NECT of abdomen showed there is focal dilatation of the extra hepatic biliary tree pushing the gall bladder anteriorly. No evidence of calculi or calcification. Gall bladder and other part of biliary tree appear normal.

MRCP shows evidence of only focal dilatation of extra hepatic biliary radical with normal appearance of other parts of extra biliary tract. Intra hepatic biliary radicals also appears normal. MRCP

DIAGNOSIS Based on the findings a diagnosis of Type I b Choledochal cyst is made, which is focal segmental dilatation of extra hepatic biliary duct which was confirmed post operatively.

DISCUSSION Choledochal cysts are congenital segmental aneurysmal dilatations of any portion of bile ducts, most commonly of the main portion of the common bile duct. Choledochal cysts are rare, with an incidence of 1:1, 00,000-1, 50,000. It is 3 to 4 times more common in females and two thirds of the patients remain asymptomatic before the age of 10.

PATHOPHYSIOLOGY 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). 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.

PATHOPHYSIOLOGY Normal development of the pancreas. The ventral pancreatic anlage is initially paired, with the left lobe subsequently disappearing during development. The ventral pancreatic anlage fuses side by side with the dorsal anlage. (b) Choledochal cysts can occur when the left ventral anlage persists and disturbs normal bile duct recanalization.

CLASSIFICATION The original classification of Alonzo-Lej has been modified by Todani et al who described five types of choledochal cysts.

Type I - most common, accounting for 80-90% (this type can present in utero) Ia - dilatation of extrahepatic bile duct (entire) Ib - dilatation of extrahepatic bile duct (focal segment) Ic - dilatation of the common bile duct portion of extrahepatic bile duct

Type II - true diverticulum from extra hepatic bile duct Type III - dilatation of extra- hepatic bile duct within duodenal wall (choledochocoele)

Type IV - next most common IVa - cysts involving both intra and extrahepatic ducts IVb - multiple dilatations / cysts of extra hepatic ducts only Type V - multiple dilatations / cysts of intra hepatic ducts only (Caroli disease)

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

In a choledochal cyst the presence of – wall thickening, – mural nodularity RAISES THE POSSIBILITY OF TUMOR – wall enhancement. 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 large choledochal cysts can be confused with large intra hepatic cystic lesions such as liver abscess, hydatid cyst on axial CT imaging alone. However the reformatted CT images and MRCP evaluation is useful in such cases which can easily show the relation of the cyst to the liver and show communication with other extra hepatic biliary ducts as seen in this case.

Complications associated with choledochal cyst include – Cholelithiasis,choledocholithiasis, cystolithiasis, – Ascending cholangitis, bile duct strictures, – Intrahepatic abscesses, biliary – Cirrhosis, portal hypertension – Hepatobiliary malignancy. Differantial Diagnosis : Duodenal diverticulum Pancreatic cystic lesions Pseudocyst(s) Cystic tumours Other causes of biliary tree dilatation Impacted gallstone Cholangiocarcinoma Biliary stricture

References 1. Savader SJ, Beneati JF, Venbrux AC et al. Choledochal cysts: classification and cholangiographic appearance. AJR 1991;156: Montana MA, Rohrmann CA. Cholangiocarcinoma in choledochal cyst: preoperative diagnosis. AJR 1986;147: [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: 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: