**6. Classification**

CCs are first classified in 1959 by Alanso-Lej and colleagues [58]. The original classification identified four types of biliary cysts (types I–IV). In 1977, Todani and colleagues [8] modified this classification and added a fifth category of CC, type V biliary cysts or Carol disease (**Figure 2**) [10]. Apart from types I–V included in the revised Todani classification, isolated cystic dilatation of the cystic duct has been described and suggested as type VI [59].

Type I CC, most commonly seen, 80–90% of all CC, is a dilatation of the extrahepatic biliary tree. Importantly, the intrahepatic biliary tree is sometimes dilated secondarily due to biliary stasis. Type I cyst can be further subdivided into type Ia, Ib, and Ic cysts [10, 60]. Type Ia CCs are composed of the gallbladder arising directly from the CC, dilated extrahepatic biliary tree, and a nondilated intrahepatic tree. Type Ib CCs are focal segmental dilatation of the CBD and contain no evidence of APBDU [50, 60]. Finally, type Ic CCs are represented by a fusiform dilatation of the common hepatic duct and CBD in the presence of APBDU [10, 50, 60], and often also a low-grade stricture at the distal CBD [50]. In type I CC, usually, gallbladder is involved in cyst structure, and cyst extends from hepatic bifurcation to duodenum [61]. Most commonly, the ducts above (right, left, and

**91**

with APBDU [63].

*Types of choledochal cysts, classified by Todani et al.*

**Figure 2.**

*Pediatric Choledochal Cysts: Unknowns are Decreasing DOI: http://dx.doi.org/10.5772/intechopen.84301*

intrahepatic ducts) and below of the CC are not dilated [14], except type Ic. In type Ic, cyst extends continuously to the common hepatic duct or intrahepatic ducts [62]. Type I CCs, along with type IV cysts, have the highest risk of malignancy [10]. This is not surprising because both of them have extrahepatic involvement associated

Type II CCs (2% of all CCs) consist of a diverticular dilatation of the extrahepatic bile duct system and is considered true diverticulum. During the diagnostic cholangiography study, the diverticulum is filled with radiopaque substance and

Type III CCs (choledochoceles), 4% of all CCs, are characterized by distal (located at the pancreaticobiliary junction) CBD dilatation, confined to the wall of the duodenum and often bulging into the duodenal lumen [25]. Type III choledochal cysts are dissimilar to other types of CCs, with features such as appearing in both sexes equally and low malignancy incidence [10, 64]. Cysts are mostly not associated with APBDU. Because of all these characteristics, it has been suggested that type III CCs should not be classified as a type of CCs revised by Todani [25, 64, 65]. In addition, Ziegler et al. reported that choledochoceles occur more frequently in older

Type IV CCs, the second most common (15–20% of all), are multiple cysts which can involve both the intrahepatic and extrahepatic biliary trees. Type IV CC

can be confused with the gall bladder duplication seen rarely [10].

male patients presenting with acute pancreatitis [64].

*Pediatric Choledochal Cysts: Unknowns are Decreasing DOI: http://dx.doi.org/10.5772/intechopen.84301*

*Pediatric Surgery, Flowcharts and Clinical Algorithms*

The association of CC with congenital anomalies remains ambiguous. Previous reports have demonstrated an association of pediatric CC and congenital anomalies. Murphy et al. reported in 2012 that screening for cardiac anomalies may be prudent in CC patients [51]. Other reports have postulated an association of CC with duodenal atresia, colonic atresia, gastroschisis, annular pancreas, and pancreatic

CCs are first classified in 1959 by Alanso-Lej and colleagues [58]. The original classification identified four types of biliary cysts (types I–IV). In 1977, Todani and colleagues [8] modified this classification and added a fifth category of CC, type V biliary cysts or Carol disease (**Figure 2**) [10]. Apart from types I–V included in the revised Todani classification, isolated cystic dilatation of the cystic duct has been

Type I CC, most commonly seen, 80–90% of all CC, is a dilatation of the extrahepatic biliary tree. Importantly, the intrahepatic biliary tree is sometimes dilated secondarily due to biliary stasis. Type I cyst can be further subdivided into type Ia, Ib, and Ic cysts [10, 60]. Type Ia CCs are composed of the gallbladder arising directly from the CC, dilated extrahepatic biliary tree, and a nondilated intrahepatic tree. Type Ib CCs are focal segmental dilatation of the CBD and contain no evidence of APBDU [50, 60]. Finally, type Ic CCs are represented by a fusiform dilatation of the common hepatic duct and CBD in the presence of APBDU [10, 50, 60], and often also a low-grade stricture at the distal CBD [50]. In type I CC, usually, gallbladder is involved in cyst structure, and cyst extends from hepatic bifurcation to duodenum [61]. Most commonly, the ducts above (right, left, and

**90**

cysts [10, 52–57].

*Anomalous pancreaticobiliary union.*

**Figure 1.**

**6. Classification**

described and suggested as type VI [59].

**Figure 2.** *Types of choledochal cysts, classified by Todani et al.*

intrahepatic ducts) and below of the CC are not dilated [14], except type Ic. In type Ic, cyst extends continuously to the common hepatic duct or intrahepatic ducts [62]. Type I CCs, along with type IV cysts, have the highest risk of malignancy [10]. This is not surprising because both of them have extrahepatic involvement associated with APBDU [63].

Type II CCs (2% of all CCs) consist of a diverticular dilatation of the extrahepatic bile duct system and is considered true diverticulum. During the diagnostic cholangiography study, the diverticulum is filled with radiopaque substance and can be confused with the gall bladder duplication seen rarely [10].

Type III CCs (choledochoceles), 4% of all CCs, are characterized by distal (located at the pancreaticobiliary junction) CBD dilatation, confined to the wall of the duodenum and often bulging into the duodenal lumen [25]. Type III choledochal cysts are dissimilar to other types of CCs, with features such as appearing in both sexes equally and low malignancy incidence [10, 64]. Cysts are mostly not associated with APBDU. Because of all these characteristics, it has been suggested that type III CCs should not be classified as a type of CCs revised by Todani [25, 64, 65]. In addition, Ziegler et al. reported that choledochoceles occur more frequently in older male patients presenting with acute pancreatitis [64].

Type IV CCs, the second most common (15–20% of all), are multiple cysts which can involve both the intrahepatic and extrahepatic biliary trees. Type IV CC can be further subdivided into type IVa and IVb cysts depending on intrahepatic involvement. Type IVa CC refers to multiple segmental communicating biliary dilatations located in the intra- and extrahepatic biliary tracts, and relative stricture at the junction that is used to distinguish the true type IVa CC from type I [11]. Type IVa CCs are usually associated with APBDU [50]. Type IVb CC refers to multiple extrahepatic biliary cysts without intrahepatic involvement [25]. Some recent studies have shown that intrahepatic ductal dilatations seen on preoperative imaging are thought to have been caused by distal obstruction and not true intrahepatic biliary duct disease [11]. Additionally, the question of "Is the distinguishing type I from type IVa really necessary preoperatively?" has not answered yet. Because distinguishing between types I and IVa CCs is controversial for some authors due to complete excision of the extrahepatic bile ducts, and intensive long-term follow-up still remains standard of care for both types [11].

Type V CC or Carol disease, added by Todani, is characterized by multifocal segmental intrahepatic biliary ductal dilatation [14] without the evidence of extrahepatic dilatation [66]. Caroli disease is uncommon, accounting for less than 10% of cases. Patients often present in adolescence or early adulthood with recurrent cholangitis, abdominal pain, or jaundice. However, they may present later with the sequel of portal hypertension and cirrhosis [67]. Renal abnormalities, such as medullary sponge kidney, autosomal dominant polycystic kidney disease, and medullary cystic disease can be seen in Caroli disease [49]. Some authors call Caroli disease as Caroli syndrome when congenital hepatic fibrosis is also seen, as in half of the patients [68, 69].

Type VI CC, isolated cystic dilatation of the cystic duct, is rare with only several case reports describing it. Although it is not officially part of the revised Todani classification, it has been proposed to be called type VI CC [70]. If the cyst emerges from the cystic duct near a level close to the CBD, it can be confused with type II CCs. In such cases, the relation of the cyst with the cystic duct should be thoroughly evaluated to differentiate them [59].

## **7. Clinical presentation**

Type IC cysts are the earliest cysts that can be detected by 15-gestational week fetal ultrasonography [71, 72]. There are two clinical forms of disease: adult and infant. In infant form, symptoms such as obstructive jaundice, clay colored stools, and hepatomegaly make it difficult to distinguish from biliary atresia. Adult form of CCs is also congenital, although they usually remain silent until the age of 2 years. There are three main symptoms in the classical clinical triad: recurrent jaundice 69–75%, right upper quadrant pain 47–60%, and right upper quadrant mass 47–80%. But the classic triad only presents in 10% of cases (6–25%) [46, 73, 74].

Abdominal pain is the most common symptom (93.8%) [75], especially in older patients and presents with colic pattern which has a variable interval time (between attacks) up to several years. When investigating the cause of CBD dilatation and differential diagnosis of unclear upper abdominal pain, jaundice, and pancreatitis in children, CCs must be considered [76]. Unfortunately, 29–62% of pediatric patients with CC have been reported that they have choledocholithiasis [77, 78], that is, distinguishing this two situation (CC-associated choledocholithiasis and -nonassociated choledocholithiasis) may be difficult. Choledocholithiasis can also lead to CBD dilatation which can be misdiagnosed as a CC [79].

In 1–2% of cases, especially in infants, CCs may present with rupture and biliary peritonitis prompting emergency biliary drainage [80, 81]. It is not a surprise in diagnosing pancreatitis in patients with CC, because of association of the presence of APBDU [10, 46, 82].

**93**

*Pediatric Choledochal Cysts: Unknowns are Decreasing DOI: http://dx.doi.org/10.5772/intechopen.84301*

**8. Diagnostic evaluation**

be shown by US [86].

The risk for development of biliary carcinoma in the general population starts after the fourth decade and the incidence increase with age to 0.15% after the eighth decade. However, the risk for the development of carcinoma in patients with a CC starts in childhood and shows a significant increase with age. Interestingly, the age of biliary carcinoma development in patients who have undergone internal drainage without cyst excision has been reported to be 15 years earlier on average than patients who have never had surgery. This is thought to be associated with intestinal bacterial contamination and pancreatic enzymes added to biliary stasis [83]. The malignancy incidence in resected bile duct material has been reported as 7.5% for all age groups, and 0.4 and 11.4% for those under and over the age of 18, respectively. The incidence has been reported to gradually increase every decade to 38.2% over the age of 60, possibly related to chronic inflammation [5]. The incidence of a biliary malignancy development following CC excision is reported as 0.7–5.4%. The malignancy can arise from anywhere such as the porta hepatis, pancreas, or the intrahepatic bile ducts. The time to onset after primary surgical intervention is reported to be 1–34 years. The total excision of the cyst significantly decreases the probability of a malignancy although it does not eliminate it completely [84, 85].

Ultimately, multimodality imaging techniques are often utilized including computed tomography (CT), magnetic resonance imaging (MRI), and/or endoscopic retrograde cholangiopancreatography (ERCP) to confirm the extent of ductal involvement or the presence of extrahepatic disease [25]. Frequently, further imaging techniques are used to differentiate type I CC from type IVa, in the presence of intrahepatic biliary dilatation [11]. A cyst, presenting in the porta hepatitis, separated from the gallbladder and continuing with enlarged biliary ducts can be shown by ultrasound (US). Additionally, fusiform dilatation of choledoch, intrahepatic biliary dilatation (60–80%), biliary stones, and state of liver parenchyma can

Other intraabdominal cysts, such as pancreatic pseudocysts, echinococcal cysts, or biliary cystadenomas should also be differentiated from CCs, whether the cyst has continuity with the biliary tree or not [40]. CT is not only useful for demonstrating continuity of the cyst with the biliary tree, but also demonstrates relation of the cyst with the surrounding structures and the presence of associated malignancy [87]. In order to correctly plan surgery, CT cholangiography can be used to identify the full anatomy of the biliary tree but unfortunately it has been reported to be less sensitive for imaging the pancreatic duct which is responsible for the reflux of contrast into the biliary ducts [87]. As it is well known today, the nephrohepatotoxicity of the contrast and the ionized radiation exposed are the restrictions

MRCP is noninvasive and highly sensitive (70–100%) and specific (90–100%) in the diagnosis of CCs [88, 89], so, is considered the current gold standard imaging even for initial evaluation [62]. Additionally, there is no irradiation, and modern scanners have alleviated the need for protracted breath-hold making it more amenable to the pediatric population [10, 90]. Although both ultrasound and CT are highly sensitive and specific in the diagnosis of CCs, MRCP can better identify the CCs subtypes and coexisting abnormalities [89]. For example, MRI can easily identify the pancreaticobiliary ductal anatomy, while ultrasound cannot accurately demonstrate the APBDU [89, 91]. Additionally, MRCP is preferred modality in the pediatric population due to invasive nature and inherent risks of endoscopic ultrasound and ERCP, despite their ability of detecting the abnormality of the common

of CT utilization in pediatric population (**Figure 3**) [62].

*Pediatric Choledochal Cysts: Unknowns are Decreasing DOI: http://dx.doi.org/10.5772/intechopen.84301*

*Pediatric Surgery, Flowcharts and Clinical Algorithms*

still remains standard of care for both types [11].

evaluated to differentiate them [59].

**7. Clinical presentation**

can be further subdivided into type IVa and IVb cysts depending on intrahepatic involvement. Type IVa CC refers to multiple segmental communicating biliary dilatations located in the intra- and extrahepatic biliary tracts, and relative stricture at the junction that is used to distinguish the true type IVa CC from type I [11]. Type IVa CCs are usually associated with APBDU [50]. Type IVb CC refers to multiple extrahepatic biliary cysts without intrahepatic involvement [25]. Some recent studies have shown that intrahepatic ductal dilatations seen on preoperative imaging are thought to have been caused by distal obstruction and not true intrahepatic biliary duct disease [11]. Additionally, the question of "Is the distinguishing type I from type IVa really necessary preoperatively?" has not answered yet. Because distinguishing between types I and IVa CCs is controversial for some authors due to complete excision of the extrahepatic bile ducts, and intensive long-term follow-up

Type V CC or Carol disease, added by Todani, is characterized by multifocal segmental intrahepatic biliary ductal dilatation [14] without the evidence of extrahepatic dilatation [66]. Caroli disease is uncommon, accounting for less than 10% of cases. Patients often present in adolescence or early adulthood with recurrent cholangitis, abdominal pain, or jaundice. However, they may present later with the sequel of portal hypertension and cirrhosis [67]. Renal abnormalities, such as medullary sponge kidney, autosomal dominant polycystic kidney disease, and medullary cystic disease can be seen in Caroli disease [49]. Some authors call Caroli disease as Caroli syndrome

Type VI CC, isolated cystic dilatation of the cystic duct, is rare with only several case reports describing it. Although it is not officially part of the revised Todani classification, it has been proposed to be called type VI CC [70]. If the cyst emerges from the cystic duct near a level close to the CBD, it can be confused with type II CCs. In such cases, the relation of the cyst with the cystic duct should be thoroughly

Type IC cysts are the earliest cysts that can be detected by 15-gestational week fetal ultrasonography [71, 72]. There are two clinical forms of disease: adult and infant. In infant form, symptoms such as obstructive jaundice, clay colored stools, and hepatomegaly make it difficult to distinguish from biliary atresia. Adult form of CCs is also congenital, although they usually remain silent until the age of 2 years. There are three main symptoms in the classical clinical triad: recurrent jaundice 69–75%, right upper quadrant pain 47–60%, and right upper quadrant mass 47–80%. But the classic triad only presents in 10% of cases (6–25%) [46, 73, 74]. Abdominal pain is the most common symptom (93.8%) [75], especially in older patients and presents with colic pattern which has a variable interval time (between attacks) up to several years. When investigating the cause of CBD dilatation and differential diagnosis of unclear upper abdominal pain, jaundice, and pancreatitis in children, CCs must be considered [76]. Unfortunately, 29–62% of pediatric patients with CC have been reported that they have choledocholithiasis [77, 78], that is, distinguishing this two situation (CC-associated choledocholithiasis and -nonassociated choledocholithiasis) may be difficult. Choledocholithiasis can also

In 1–2% of cases, especially in infants, CCs may present with rupture and biliary peritonitis prompting emergency biliary drainage [80, 81]. It is not a surprise in diagnosing pancreatitis in patients with CC, because of association of the presence

lead to CBD dilatation which can be misdiagnosed as a CC [79].

when congenital hepatic fibrosis is also seen, as in half of the patients [68, 69].

**92**

of APBDU [10, 46, 82].

The risk for development of biliary carcinoma in the general population starts after the fourth decade and the incidence increase with age to 0.15% after the eighth decade. However, the risk for the development of carcinoma in patients with a CC starts in childhood and shows a significant increase with age. Interestingly, the age of biliary carcinoma development in patients who have undergone internal drainage without cyst excision has been reported to be 15 years earlier on average than patients who have never had surgery. This is thought to be associated with intestinal bacterial contamination and pancreatic enzymes added to biliary stasis [83]. The malignancy incidence in resected bile duct material has been reported as 7.5% for all age groups, and 0.4 and 11.4% for those under and over the age of 18, respectively. The incidence has been reported to gradually increase every decade to 38.2% over the age of 60, possibly related to chronic inflammation [5]. The incidence of a biliary malignancy development following CC excision is reported as 0.7–5.4%. The malignancy can arise from anywhere such as the porta hepatis, pancreas, or the intrahepatic bile ducts. The time to onset after primary surgical intervention is reported to be 1–34 years. The total excision of the cyst significantly decreases the probability of a malignancy although it does not eliminate it completely [84, 85].
