Patients with choledochal cysts present with a wide variety of symptoms, usually complications of the cysts such as cholangitis , cholecystitis, and pancreatitis, or may remain completely asymptomatic with incidental discovery of the lesion(s) [4, 57]. Between 50 and 80 % of patients with choledochal cysts are diagnosed in the first decade of life [29, 51]. The classic triad of abdominal pain, jaundice, and a palpable abdominal mass is more common in younger patients. Although over 60 % of patients have two out of three symptoms, only 20 % will have all three [2, 55, 57]. In younger patients, obstructive jaundice and a palpable abdominal mass are the most common symptoms. In older patients, symptoms related to mass effect or bile stasis within the cyst, such as RUQ abdominal pain, nausea, vomiting, and fever, are more common. Bile stasis can lead to stone formation and infection, which may result in secondary biliary cirrhosis [42]. These patients may present with signs and symptoms of cirrhosis including variceal bleeding , splenomegaly, and pancytopenia. Portal hypertension may also occur without cirrhosis due to the choledochal cyst causing mechanical obstruction of the portal vein. Rarely, patients present with life-threatening complications such as cyst rupture (1–12 %), variceal bleeding from portal hypertension, liver abscesses, or sepsis [23, 57]. Cyst rupture presents with abdominal pain, sepsis, and bile peritonitis with abdominal ultrasound (US) potentially demonstrating a normal biliary tree if the cyst decompressed following rupture. A hepatobiliary iminodiacetic acid (HIDA) scan will show contrast entering the peritoneal cavity.

While patients with choledochoceles may have symptoms similar to other choledochal cysts , they are often asymptomatic. Type III choledochal cysts can also rarely present with gastric outlet obstruction if a large intramural cyst bulges into the duodenal lumen [41, 57].

Although many patients are asymptomatic, many adult patients will develop complications from choledochal cysts [28]. Symptoms may arise in any part of the biliary tract, often due to mechanical obstruction either from mass effect by the cyst or from stones in the ducts, which can lead to ascending cholangitis or pancreatitis [57]. The severity of recurrent episodes of inflammation and infection is likely to escalate if left untreated. Secondary changes, including portal hypertension, cirrhosis, and malignancy , occur much more often in adults than in children [55].

Cancer is common in patients with choledochal cysts (Table 10.1). Cholangiocarcinoma accounts for nearly two-third of these malignancies followed by gallbladder cancer, with rare occurrences of hepatocellular carcinoma, and pancreatic cancer [57]. Cancer typically develops within the choledochal cysts and in the gallbladder of patients with forme fruste cysts. While all choledochal cysts are premalignant, and cancer has been reported in all Todani classes, types I and IV account for the vast majority of cancers (68 and 21 %, respectively) [63]. The overall incidence of malignancy in patients with choledochal cysts is between 2.5 and 28 %, which is 20 to 120 times greater than the general population [38, 55, 57]. In addition, patients with choledochal cysts are typically diagnosed with malignancy 10–20 years earlier than the general population, and have a worse prognosis with few surviving beyond 2 years from diagnosis [54, 57, 70].

The risk of malignancy in patients with choledochal cysts increases with age (Table 10.2). In patients younger than 10, the cancer risk is less than 1 % [18]. The risk of cancer increases to 2.3 % in patients over 20, over 10 % by age 30, and 75 % by age 70 [5, 50]. Even after surgical resection of a choledochal cyst, patients are at increased risk for developing cancer. Assuming the cyst is completely excised, there is negligible risk of malignancy for the first three decades following surgery. The risk then rises with each decade after resection to 19 % between 30 and 50 years and 50 % for patients 50–70 years following surgery [36]. The literature suggests this is due to the remnant cyst tissue or subclinical malignant disease not detected or excised at the time of surgery [18].

Serum liver chemistries are generally not useful in the diagnosis of choledochal cysts, as there is no pathognomonic laboratory pattern for choledochal cysts. They may be normal, although elevations of transaminases or bilirubin from cholangitis are common. Without pathognomonic physical examination findings or laboratory values, imaging becomes the definitive tool for diagnosis of choledochal cysts . The goals of imaging studies include determining whether the cyst communicates with the bile duct, and evaluating for the presence of a mass. Numerous imaging modalities, both invasive and noninvasive, can be utilized to characterize the choledochal cysts. Noninvasive imaging with transabdominal US, CT, magnetic resonance imaging (MRI), and MRCP, as well as invasive imaging modalities such as ERCP , endoscopic ultrasound (EUS) , and percutaneous transhepatic cholangiography (PTC) are used to diagnose choledochal cysts. The most common cause of bile duct dilation is obstruction, not biliary cysts. Biliary cysts communicate with the biliary tract, and do not result from distal obstruction [26]. Cholangiographic studies, including ERCP, MRCP, and PTC, are used to show continuity with the biliary tract, rule out obstruction, define the anatomy of the biliary tree, and more fully characterize the choledochal cyst.

Transabdominal ultrasound is often the first modality used to evaluate patients who present with abdominal pain and jaundice. Characteristic findings of choledochal cysts are a nonobstructive mass in the RUQ that communicates with the biliary tract [22]. US can be used to evaluate the size and shape of the cysts, its relationship to other components of the biliary tract, and whether there are stones or sludge present within the cyst. The sensitivity of US to diagnose choledochal cysts ranges between 71 and 97 %, though limited by many factors, including the skill of the technician and the patient’s body habitus, gas pattern, and overlying structures [14, 16]. The “central dot” sign (dilated duct surrounding a portal bundle) seen only in Todani type V cysts is nearly pathognomonic for Caroli disease. Todani type III cysts are difficult to identify on transabdominal ultrasound because of their smaller size, location within or at the level of the duodenal wall, and less dilated CBD [57]. Although more invasive than transabdominal US, EUS is not affected by the factors that limit transabdominal US imaging, and is particularly useful for visualizing the intrapancreatic portion of the CBD as is desired in patients with type III cysts [53, 57]. EUS can provide more detailed imaging of the pancreaticobiliary junction as well.

Antenatal US has been used to diagnose choledochal cysts in utero well before symptoms manifest [31]. It is a useful tool to distinguish choledochal cysts from other masses in the RUQ-like biliary atresia , which usually require emergent surgery [18, 66].

CT scan visualizes the continuity between the cysts and the biliary tree in all five Todani classes, and is superior to US at characterizing the intrahepatic biliary system, distal bile duct, and the head of the pancreas [57]. Extrahepatic malignancies can appear as a mass or focal wall thickening [37]. CT scan also shows the architecture of the liver and intrahepatic lesions, which in type IV or V cysts can be useful in preoperative planning to determine if segmental lobectomy is feasible. It may be superior to MRI for postoperative monitoring as well [33]. Computed tomographic cholangiopancreatography (CTCP) utilizes CT images with infusion of iodipamide meglumine that is absorbed by hepatocytes and excreted into the bile to visualize the biliary tract [19]. Though highly sensitive (90 %) for visualizing the biliary tree and diagnosing both choledochal cysts and cholelithiasis, it is inferior to MRCP, EUS , and ERCP in visualizing the intrahepatic and pancreatic ducts [13, 25]. Further shortcomings of CT and CTCP include radiation exposure and potential nephrotoxicity from the intravenous contrast.

HIDA scan is a nuclear medicine study used to demonstrate continuity between the cysts and the biliary tract. Dye absorbed by hepatocytes collects in bile and fills the cyst with delayed emptying into the bowel [18, 57]. The sensitivity is nearly 100 % for identifying extrahepatic cysts but decreases significantly to 67 % with intrahepatic cysts [36]. HIDA scan can be particularly useful for distinguishing choledochal cysts from biliary atresia in the neonate with excretion seen in cysts and retention of contrast in biliary atresia.

MRCP is a noninvasive evaluation of the biliary tract with very high sensitivity for diagnosing choledochal cysts, reported between 90 and 100 %. MRCP has been used for diagnosis , preoperative planning, and postoperative monitoring and is typically performed before ERCP. Compared to ERCP, MRCP is safer with no radiation exposure or risk of pancreatitis and cholangitis , and image acquisition is not operator dependent. Secretin stimulation may increase diagnostic accuracy, and newer, faster sequencing techniques minimize motion artifacts, make image acquisition more tolerable for adults, and allow children to be imaged without anesthesia [8, 12, 33, 72]. Although MRCP is considered by some to have replaced ERCP as the gold standard for diagnosing choledochal cysts , it does not allow direct evaluation of biliary epithelium, tissue sampling, or therapeutic maneuvers [33, 40, 55, 57]. In addition, MRCP is inferior at evaluating highly tortuous ducts, small structures, small stones, and the pancreaticobiliary junction, with sensitivity as low as 46–60 % [24]. Therefore, the diagnosis of APBJ and small choledochoceles is limited with MRCP.

ERCP is the gold standard for diagnosing choledochal cysts with sensitivity approaching 100 % [21]. It detects stones and filling defects, identifies malignancy, and characterizes abnormal pancreaticobiliary junctions. In addition to being highly sensitive, ERCP allows the operator to pursue further imaging, such as pancreatography, cholangioscopy , or intraductal and/or EUS in the same session. Perhaps the greatest benefit of ERCP is the ability to perform therapeutic interventions such as sphincterotomy (as is commonly performed for type III cysts). However, the incidence of post-ERCP pancreatitis is much higher in patients with choledochal cysts, with some reports as high as 87 % [56]. In addition, large cysts require larger dye loads, which can dilate the cyst resulting in overestimation of cyst size and obscuring mucosal defects including ulcers and malignancies [32, 57].

Cholangioscopy involves passing a small fiber optic camera during ERCP into the bile duct to more fully evaluate the biliary tree [61]. It can be used diagnostically to evaluate cyst shape and size and biopsy from the bile duct or therapeutically to break up and remove stones. Compared to traditional ERCP with brush biopsy, cholangioscopic-guided biopsy has higher sensitivity and specificity for diagnosing cholangiocarcinoma in patients with congenital cystic dilations [11, 36]. Intraductal ultrasound (IDUS) has also been used to diagnose early malignant changes in choledochal cysts [73]. The procedure is performed during ERCP over a guidewire to characterize the pancreatic and bile ducts [20]. The probe has a penetration depth of around 2.0 cm, and is very sensitive at visualizing luminal abnormalities. The maneuverability of the probe may be hindered by strictures within the duct.

Patients should undergo MRCP preferably to further evaluate possible choledochal cysts that were detected on abdominal US and/or abdominal CT. If uncertainty remains over whether the cyst communicates with the bile duct, HIDA scan should likely be the next step although ERCP can be performed as well. For suspected type III cysts, ERCP should be pursued for both diagnostics and therapeutics. ERCP can also be used if MRCP cannot be performed or is inadequate, biliary obstruction cannot be ruled out, or there are concerns about malignant transformation. Cholangioscopy and IDUS can be used to examine the bile duct walls during ERCP and look for concerning areas that would warrant biopsy and brushing. In general, the authors do not advocate random brushings of normal appearing choledochal cyst walls, as this likely has a very low yield. Type I choledochal cysts may be difficult to differentiate from biliary obstruction, leading to secondary biliary dilation and may require further evaluation with EUS or ERCP. Clues supporting a diagnosis of biliary obstruction include presence of stones, stricture, mass, abnormal LFTs, and improvement of biliary dilation after treatment. On the other hand, presence of APBJ implies a choledochal cyst.