Choledochal Cyst of the Cystic Duct - A Supplement to Todani's Classification.

Choledochal cyst of the cystic duct is a rare anomaly; broadly classified, the pathology may either present as a solitary anomaly or with concomitant involvement of other parts of the biliary tree. In the absence of standard guidelines for surgical planning, the definitive management is based on the experience shared in the literature in the form of case reports and case series. The available options should be discussed with the patient while explaining the possible short- and long-term complications. The authors herewith present two cases of choledochal cyst of the cystic duct along with a review of literature relevant to their etiopathogenesis and its implications for the definitive management. Copyright:

INTRODUCTION

The term “choledochal cyst” refers to congenital pathological dilatation of any part of the bile duct. The original classification (Alonso-Lej) was upgraded in 1977 to include the intrahepatic cysts under the umbrella of congenital bile duct cysts or biliary cysts. The revised classification was based on the anatomic location of the cyst and the cholangiographic morphology; yet it failed to be absolute. Cysts arising from the cystic duct either solitarily or involving other anatomical components of the biliary tree were excluded although the first description of this condition in the medical literature can be traced back to Stoppa et al. in 1965.

The authors herewith present two cases of choledochal cyst of the cystic duct along with a review of literature relevant to their etiopathogenesis and its implications for the definitive management.

CASE REPORTS

Case 1

A 12-year-old boy with no known congenital anomaly presented with recurrent, self-limited, colicky, right upper quadrant abdominal pain which was aggravated after fatty meals and Associated with occasional nonbilious vomiting for the past 1.5 years. Physical examination was unremarkable and so was the routine workup (hematology and liver function tests).

Sonography of the abdomen revealed a distended gallbladder (GB) with 1.2 cm long, grossly dilated, and tortuous cystic duct [Figure 1a and b]. There was focal dilatation of common bile duct (CBD) at the site of cystic duct insertion which was “wide.” The common hepatic duct (CHD) was dilated in its distal three-fourth, while the proximal CHDs as well as the right and left hepatic ducts were normal in appearance and caliber. The intrahepatic biliary radicles (IHBRs) were not dilated.

Figure 1

(Patient 1): Case of choledochal cyst of the cystic duct. (a and b) Sonographic images showing gross dilatation of the cystic duct (highlighted by the white arrow) inserting into the dilated proximal biliary duct. There was no dilatation of intrahepatic biliary radicles and gallbladder was distended, (c) steady-state free precession image showing dilatation (white arrow) of the cystic duct, (d) heavily T2-weighted HASTE image showing dilatation of biliary duct (white arrow)

Magnetic resonance cholangiopancreatography (MRCP) was peculiar with dilatation of the cystic duct (the widest transverse diameter being 14 mm) and the CHD [Figure 1c and d].

Intraoperative cholangiogram [Figure 2a] confirmed the findings on preoperative imaging: distended GB, dilated and tortuous cystic duct, and dilated CBD. The cystic duct was opening into the CBD through a wide orifice. The IHBR and CBD distal to insertion of the cystic duct were normal. The main pancreatic duct was well visualized and not dilated. The junction of the CBD and the pancreatic duct was anomalous and peculiar with a long common channel. Free flow of contrast into the duodenum was observed and so was the opacification of the main pancreatic duct.

Figure 2

(Patient 1): Case of choledochal cyst of the cystic duct. (a) Intraoperative cholangiogram confirming the findings upon preoperative imaging with distended GB (1), dilated cystic duct (2), dilated proximal biliary duct (3), and normal caliber of intrahepatic biliary radicles and distal CBD (4). (b) Operative photograph. Laparotomy was performed by a roof-top incision, (1) GB dissected off its bed, (2) dilated cystic duct and (3) dilated common hepatic duct. GB: Gallbladder, CBD: Common bile duct

Similar findings were noted upon surgical dissection [Figure 2b]. Proximal CHD was found to be normal. Cholecystectomy, excision of choledochal cyst, and the extrahepatic biliary tree beyond the normal CHD were performed, and the continuity of the biliary tree was re-established through a Roux-en-Y hepaticojejunostomy.

The postoperative recovery was uneventful.

The histopathology was consistent with the diagnosis of choledochal cyst, with no evidence of atypia.

The patient continues to be in regular follow-up and asymptomatic at 2 years of follow-up.

Case 2

A 7-year-old girl presented with a history of pain in the upper abdomen post-lunch, for which she had to be recalled home prematurely on three occasions during the preceeding 10 days. There was a history of low-grade fever and dyspepsia in the last few days before presentation. Examination of the abdomen suggested minimal-to-mild tenderness upon deep palpation in the right upper quadrant, which was consistent with the classical Murphy's sign. Serum alkaline phosphatase was minimally elevated, while the other parameters of liver function tests were undisturbed. Sonographic evaluation of the abdomen suggested the presence of a distended GB with a long, dilated, and tortuous cystic duct (13 mm). The CBD was also dilated, mildly though in its entirety. The IHBRs were not dilated. The findings upon ultrasonography were confirmed with MRCP [Figure 3a and b]. In addition to the cystic duct and the CBD, the CHD was also dilated distal to the confluence. The pancreatic duct was entering the CBD outside the sphincter of Oddi. Tiny calculi were present in the dependent portion of the distal, mildly dilated CBD.

Figure 3

(Patient 2): Case of choledochal cyst of the cystic duct. (a) T2-weighted magnetic resonance images showing dilatation of the cystic duct (highlighted by white arrow), (b) dilatation of the cystic duct (1) and incidentally tiny calculi (2) were also seen in the dependent regions of mildly dilated common bile duct

Surgery was suggested, but the patient did not return after the outpatient department-based preanesthesia workup.

DISCUSSION

Choledochal cyst of the cystic duct is a rare condition. Much of the information on this entity is available in the form of case reports and case series only. The normal cystic duct measures 2–4 cm in length and varies from 1 to 5 mm in diameter, and a cystic duct diameter of >5 mm and <10 mm is considered as mild dilatation in the context this disease.[1]

The dilatation of the cystic duct in patients with choledochal cyst[23] may result in accentuated acuteness of angulation at the CHD–cystic duct junction. This, in conjunction with the wider orifice of the cystic duct into the CBD, may serve to redirect the refluxed enzymes into the cystic duct.

The Babbitt's theory, however, does not explain why the CBD is spared in cases with isolated involvement of the cystic duct. The vulnerability of the cystic duct may be explained by the vascularity which is least at the junction of the cystic duct with the CBD.[4] The pancreaticobiliary junction was abnormal in both the index cases; however, the abnormal junction is not associated with choledochal cyst uniformly, and the possibility of other mechanisms cannot be negated.

The definitive management of choledochal cyst of the cystic duct is surgical; the surgical plan is generally dictated by several factors: (a) anatomy of the biliary tree, (b) opening of the cystic duct into the CBD, (c) presence of anomalous pancreaticobiliary junction, (d) age of the patient, and (d) available of surgical expertise. Besides an aid in diagnosis, the importance of MRCP and intraoperative cholangiogram lies in defining the precise anatomy of the biliary tree.

An extensive search for the choledochal cyst of the cystic duct on open-domain search engines (PubMed and Google Scholar) identified several variants of the disease; broadly classified, the pathology may either present as a solitary anomaly or with concomitant involvement of other parts of the biliary tree. The orifice of the cystic duct into the CBD has been further subclassified into narrow or wide. Precise information upon the acceptable size of the cystic duct–CBD orifice is not available. Inability to negotiate a K90 tube (external orifice >20 F) into the cystic duct–CBD orifice was considered diagnostic for a narrow orifice in one study,[5] while a 2.2-mm orifice in a 32-year-old male was considered normal in another study.[6]

Choledochal cyst of the cystic duct as a solitary anomaly with a narrow opening into the CBD may be managed by simple cholecystectomy with excision of the dilated cystic duct. The procedure has been completed by both the “open approach” and “laparoscopy.” The approach may be governed by the availability of surgical expertise for both open cholecystectomy and minimally invasive approach. However, the presence of an anomalous pancreaticobiliary junction may be an indication for a more extensive resection

Choledochal cyst of the cystic duct as a solitary anomaly with a wide opening into the CBD precludes safe clipping. Besides, the CBD may be abnormal. Complete excision of the cyst along with the involved CBD followed by bilioenteric reconstruction with a Roux-en-Y hepaticojejunostomy is suggested. Simple closure of the wide CBD orifice has been reported; the risks of leak, stricture, and malignancy may, however, not be excluded

Presence of an anomalous pancreaticobiliary junction should be considered as an indication for CBD excision to stop the reflux of pancreatic juices into the biliary tree. This may reduce the risk of malignant transformation somewhere in the biliary tract later in life, at least partially

Age of the patients, especially those in the second extreme, is an important factor in deciding the line of management. Maheshwari has reported observation in a 75-year-old man with isolated distinct saccular cystic duct involvement in view of age and absence of complications[1]

Surgical plan in a case of choledochal cyst of the cystic duct with concomitant involvement of other parts of the biliary tree is formulated in accordance with the standard recommendations (as per classification by Todani et al.) in conjunction with the concerns highlighted in this report.

A long-term surveillance for malignant transformation cannot be overemphasized.

In the absence of standard guidelines on the definitive management and the scarcity of long-term outcomes of this anomaly, the authors suggest that the available operative options should be discussed with the patient and the family (more relevant for pediatric cases) while explaining the possible short- and long-term complications.

CONCLUSIONS

Choledochal cyst is a rare anomaly; choledochal cyst of the cystic duct is rarer. The available information is in the form of limited case reports or case series in the literature.

The definitive management of choledochal cyst of the cystic duct is surgical; the surgical plan is governed by several factors: (a) anatomy of the biliary tree, (b) opening of the cystic duct into the CBD, (c) presence of anomalous pancreaticobiliary junction, (d) age of the patient, and (e) available of surgical expertise.

In the absence of standard guidelines for management, the available options should be discussed with the patient while explaining the possible short- and long-term complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.