Intrahepatic Class VII Choledochal Cyst: Radiological Insights and Surgical Approach

Introduction

Cystic dilations of the intrahepatic, extrahepatic, or both ducts are known as choledochal cysts. They have a high risk of mortality and considerable morbidity if improperly identified and managed. In Asia, choledochal cysts are more common in female patients, with a female: male ratio of 4: 1. The incidence ranges from 1 in 13 000 to 1 in 2 million births. About 60% of cases manifest early, in the first year of life [1–3], and the presenting symptoms range from abdominal pain to jaundice, and sometimes a palpable right upper quadrant mass is discovered on examination. In adults, abdominal pain is the most frequent first symptom [4].

There are 5 different anatomical subtypes of choledochal cysts reported, according to Todani’s classification. Another classification reported 6 types of isolated cystic duct dilatation [5]. In the present case, we describe a case of an intrahepatic variant of bile duct cysts originating near the confluence of the major lobar bile ducts, which was radiologically identified as biliary cyst adenoma in segments 4b and 5. Differential diagnoses of a choledochal cyst include a simple cyst or hemorrhagic cyst, hydatid cysts, liver abscess, and undifferentiated embryonal sarcoma. Other differential diagnoses include cystic lesions that can potentially communicate with the biliary radicles, such as biliary cystadenoma and cystadenocarcinoma [6,7].

Case Report

A 35-year-old female patient presented with right upper quadrant pain and a palpable mass during examination, which had been present for a long time. Other than that, she reported a healthy appetite, no weight loss, no changes in skin, eye, urine, or stool color, no itchiness, and no history of cholecystitis. She had no past history of psychological or chronic medical conditions, and there was no family history of biliary illnesses or other congenital abnormalities. Magnetic resonance cholangiopancreatography (MRCP) revealed a complicated cystic lesion that compressed the right and left proximal hepatic ducts. The lesion showed internal septation, with heterogenous T2 signal intensity, with mild intrahepatic biliary radicle dilatation at the right lobe, due to mass effect on the right hepatic duct (Figure 1). After completing all investigations and ruling out another differential diagnosis, the patient’s condition was diagnosed radiologically as biliary cyst adenoma in segments 4b and 5. During intraoperative exploration, the cyst was found to be approximately 8×7 cm. It was located intrahepatically, extended infrahepatically, and was adjacent to the gallbladder; however, it was easily separable from the gallbladder. Then, the cholecystectomy and common bile duct exploration were done. Here, the cyst was inseparable from the confluence of common hepatic duct, and there was 1 duct going over the wall of the cyst, which was expected to be the right hepatic duct. The left hepatic duct passed to the left of the cyst, which did not fit with any of the current recognized choledochal cyst classification types. The peritoneum over the cyst, which contained these ducts and was in the area of confluence, was dissected and pushed down to avoid injury; enucleation of the lower border was successfully done. The upper border was transected through the liver parenchyma, and here, many small ductules connected with the cyst were ligated (Figure 2). Postoperatively, the patient was improving, and all investigations, including cholestatic parameters, remained almost normal. The drain was emptying around 100 to 120 mL clear bile daily. Sphincterotomy plus stent implantation (endoscopic retrograde cholangiopancreatography, ERCP) was done to release the pressure in the biliary system and to decrease the amount of bile leak. Unfortunately, the patient developed subcapsular bilioma (Figure 3), which was drained later through ultrasound-guided drainage. The drainage amount of the peritoneal drain increased after ERCP and reached 300 mL per day, and after a few days, the stent was removed. The patient managed conservatively with culture-sensitive antibiotics, and the amount of drainage decreased and stopped without any intervention. Histopathological analysis showed a benign biliary type cyst with mild to moderate reactive atypia, and no malignancy was seen. Then the patient was discharged on oral antibiotics in good general condition and had normal investigations, including liver function tests and cholestatic parameters.

Discussion

Commonly, bile duct cysts are considered a pediatric illness. According to reports, congenital choledochal cysts appear in 1 in 13 000 to 1 in 200 000 live births, with female predominance [8,9]. As described in the present report, jaundice from cholestasis and abdominal pain are the main presenting symptoms. Less than 20% of cases have a palpable abdominal mass. The most typical symptom in adults is constant and alternating abdominal pain, although jaundice, palpable mass, and recurrent acute cholangitis can be associated [10]. This is consistent with what was seen in the presenting case, in which the right upper quadrant pain and an abdominal mass were reported.

Generally, the categorization of biliary cysts depends on their location, size, and shape of the cystic abnormality within the bile duct system. The first classification of choledochal cysts was proposed by Lonso-Lej et al in 1959 [10], in which 3 types were identified. In 1977, more types were introduced by Todani et al [11], to comprise intrahepatic and multiple cysts, and this new modification is still used until now. This modified classification includes the following types:Type I:Cystic dilation of the extrahepatic duct, with sparing of the intrahepatic ducts. The cystic duct and the gallbladder arise from the dilated common bile duct.Focal segmental dilation of the extrahepatic duct, mainly distal and the cystic duct is branching from a normal common bile duct while the proximal part of the biliary tree is normal.Fusiform dilation of the entire length of the extrahepatic duct, usually continues from the pancreaticobiliary connection to the intrahepatic biliary tree [12].Type II:Simple diverticula with narrow stalk connect with the common bile duct.Type III (choledochocele):Distal intramural dilation within the duodenal wall is restricted to the duodenal wall, and often expands into the duodenal lumen.Type IV:Intra- and extrahepatic bile duct dilation (combined, cystic, fusiform, or irregular) [12].Multiple extrahepatic bile duct dilations, described radiographically as either a “string of beads” or “a bunch of grapes” appearance [12].Type V:Also known as Caroli disease or communicating cavernous ectasia, is characterized by multiple intrahepatic bile duct dilation.

Type I choledochal cysts account for between 50% and 80% of all cases, followed by types IV (12–35%), V (20%), III (1.4–4.5%), and II (2–3%) [6,13,14]. Serradel et al [15] revised Todani’s categorization to include isolated cystic duct cysts and advocated a new of type VI choledochal cysts. It has been observed anecdotally that there are intrahepatic forms of bile duct cysts, with solitary saccular or fusiform cysts evolving from the major lobar bile ducts close to the confluence (Figure 4) that cannot be classified by the present typing methods. The cysts’ actual bile duct cyst or cystadenoma variant origins are unknown [14].

In the present case, the patient’s radiological diagnostic was segment 4b and segment 5 biliary cyst adenoma. An intraoperative cyst surrounded the confluence of the common hepatic duct and expanded to the gallbladder; a duct that crossed the cyst’s wall was believed to be the right hepatic duct. Following Todani’s methodology, Gidi et al suggest classifying this variation as type IV-C [6], and we propose categorizing this variant as type VII. Todani’s classification must be updated and enhanced according to several experts describing the unusual choledochal cyst types [15]. The most accurate method for diagnosing choledochal cysts and related abnormalities is ERCP. However, because of its invasiveness, ERCP has a risk of morbidity. As an alternative, magnetic resonance cholangiopancreatography is a feasible, noninvasive method that has high overall accuracy in the detection and categorization of choledochal cysts [16–19].

The complex cystic lesion that flattened the right and left proximal hepatic ducts was visible on magnetic resonance cholangiopancreatography in the present case. The best treatment for choledochal cysts is surgery. Complete excision of all cystic tissue is suggested due to the opportunity of recurrent cholangitis and the high risk of malignant transformation, which ranges from 5% to 7.5%, with the highest rates reported in types I and IV, and the lowest rates in types II and III [20,21].

In the present case, to avoid damaging the right hepatic duct or the area of confluence, the serosa above the cyst was dissected. This allowed the lower border to be safely removed. Through the liver parenchyma, the cyst’s top border was dissected, and several minor ductules that were attached to it were then ligated. Unfortunately, early postoperative complications, such as ileus, bile leakage, pancreatitis, and pancreatic fistula, might happen even with radical treatment. Subcapsular bilioma occurred in our patient, which was eventually removed using ultrasound guidance.

Conclusions

Adult choledochal cysts are uncommon. Magnetic resonance cholangiopancreatography is a feasible, noninvasive procedure with good overall accuracy in choledochal cyst diagnosis and classification. To reduce the risk of malignant transformation and avoid pancreatitis and recurring cholangitis consequences, total cyst removal is undertaken. Despite the widespread use of Todani’s categorization in clinical practice, many specialists contend that it needs to be updated and improved, considering the numerous reports of uncommon choledochal cyst types and new insight into their etiology.