Congenital choledochal cysts (CSC) are most commonly seen in children in Asia, but approximately 25% of congenital choledochal cysts develop in adulthood. With the development of biliary imaging, the detection rate of choledochal cysts in adults has increased. Because most of the symptoms of this disease are atypical or combined with hepatobiliary and pancreatic diseases, it often leads to misdiagnosis or delayed diagnosis. In recent years, with the in-depth study of the pathology, morphology and etiology of this disease, it has been found that in addition to cystic dilatation of the common bile duct, about half of the patients present with only a shuttle-shaped or cylindrical dilatation of the common bile duct rather than a giant cyst. In addition to the dilatation of the extrahepatic common bile duct, about 1/4 of the cases also had a combination of pyknotic or even small cystic dilatation of the intrahepatic bile duct.
I. Pathogenesis
Congenital cystic dilatation of the bile ducts is a surgical biliary disease with cholestasis, the etiology of which has not yet been determined. There are mainly the following theories.
1, congenital factors
(1) The theory of abnormal bile duct epithelial proliferation: The theory of congenital factors proposed by Yotsuyanagi in 1936 was accepted by most people. Alonson-Lej et al. proposed that the bile duct epithelium is vacuolated during embryonic dysplasia and the local duct wall is weak.
(2) Abnormal pancreatic and biliary duct co-flow theory: It has been found by various means that the disease almost always has abnormal pancreaticobiliary duct co-flow. Miyano indirectly proved the abnormal collateral flow by the abnormally high amylase value in the bile of dilated bile ducts.
Babbitt and John et al. found by observing the film of this patient that: (1) the junction of the main pancreatic duct and common bile duct was far from the Vater’s jugular abdomen, forming a common channel of 2 to 3.5 cm (normal <0.5 cm); (2) the main pancreatic duct and common bile duct converged at right angles, and the intra-pancreatic duct pressure was as high as 2.94 to 4.9 kPa (22.1 to 36.8 mmHg) and the intra-biliary pressure was 2.45~2.94kPa (18.4~22.1mmHg). Such characteristics lead to reflux of pancreatic juice, increased pancreatic enzyme activity, destruction of bile duct mucosa, and duct wall fibrosis. When the bile duct pressure is increased then it is easy to produce cystic dilatation. Arima et al. used selective cholangiopancreatography to perform intraoperative cholangiography in 16 patients with choledochal cysts, and all of them had abnormal connections to the pancreaticobiliary system.
(3) Neurodevelopmental anomalies theory: In 1943, Shallow pointed out that congenital choledochal cysts occur at sites with defects in nerve cells, similar to the alterations of megacolon. Yang Hongwei et al. found through histological studies of the distribution of nerves at the end of the common bile duct in normal children and fetuses and this patient that the abnormal reduction in the distribution of nerves in the stenotic segment at the end of the congenital bile duct cyst was a primary lesion. Spastic stenosis of the distal common bile duct is one of the causes of the disease, which is a congenital developmental anomaly. Abnormal pancreaticobiliary merging may coexist with abnormal nerve development at the end of the cyst. Due to the spastic stenosis in the distal segment of the abnormal nerve development, the pancreatic fluid secretion pressure is higher than the bile duct internal pressure, reflux persists and damages the bile duct wall, and the two together form a bile duct cyst. In recent years, some scholars believe that bile duct epithelial viral infection, such as hepatitis B antigen, can also cause lumen obstruction or weakness of the duct wall and produce cystic malformation and bile duct atresia.
2.Acquired factors Some scholars believe that bile duct cysts, especially adult-type bile duct cysts, are mainly due to complete or incomplete obstruction of bile ducts, resulting in bile stagnation and infection, causing fibrosis and loss of elasticity of bile duct walls, and when the pressure in bile ducts increases, secondary proximal bile duct expansion occurs, gradually forming cysts. The causes of obstruction are mostly bile duct inflammation, bile duct stones, tumors or secondary to injury. In addition, pregnancy, enlarged lymph nodes in the hilar region, pancreatic tumors, visceral prolapse and papilloma in the duodenum can lead to obstruction of the lower bile duct and cause this disease. Whether it can be denied that the cystic dilatation lesions caused by these acquired factors are predicated on the presence of underlying congenital abnormalities remains to be explored.
3. congenital factors combined with acquired factors Kozloff et al. reported a case of an adult with normal bile ducts after initial open surgery, but a common bile duct cyst was found to form during reoperation. kato et al. ligated the distal bile ducts after local scraping of the bile duct mucosa in puppies and adult dogs, resulting in bile duct cysts only in puppies but not in adult dogs. This experiment also indicates that bile duct cysts occur due to congenital weakness of the bile duct wall supplemented by acquired bile duct obstruction. The formation of bile duct cysts should generally have two conditions: narrowing of the duct wall and increased bile duct pressure, the latter necessarily presupposing obstruction of the lower bile duct.
II. Typing
Scholars at home and abroad have proposed various staging criteria from different perspectives. In terms of choledochal cyst, most scholars prefer the Alonson-Lej classification method; the current widely adopted criteria classify choledochal cysts into type V, i.e., types I to III are the same as the Alonson-Lej typology:.
Type I: cystic type, clinically common, accounting for more than 80%. The bile (common) duct is cystic or shuttle-shaped dilated, and its 3 subtypes are narrowly defined choledochal cyst, segmental common bile duct dilatation and diffuse extrahepatic bile duct dilatation.
Type II: diverticular type, with diverticula-like growths from the lateral wall of the common bile duct. The common bile duct itself is normal or mildly dilated.
Type III: Duodenal (intramural) dilatation type, in which the end of the common bile duct is cystically dilated in the duodenum and the pancreatic duct and common bile duct converge into the dilated portion.
Type IV-A: multiple cysts of intrahepatic and extrahepatic bile ducts.
Type IV-B: multiple cysts of extrahepatic bile ducts.
Type V: single or multiple cysts in the intrahepatic bile duct (Caroli disease).
III. Morbidity
Congenital bile duct cysts are more common in females, accounting for about 62%-74%. (Type I accounts for about 90%, type II accounts for about 2%, type III accounts for about 1.5%).
IV. Clinical manifestations
1, abdominal pain: mostly confined to the upper abdomen, right upper abdomen or around the umbilicus, the nature of the pain is more colic, but can also be manifested as persistent or intermittent dull pain, distension or pulling pain, sometimes high fat or excess diet can trigger the occurrence of abdominal pain. The manifestations of abdominal pain in young children are often misdiagnosed because they cannot be told. Infants and young children often have abdominal pain in a kneeling position with the head and shoulders down, which seems to be a reference for the manifestation of abdominal pain. Some children have recurrent episodes of abdominal pain that last for months or even years, and the pain episodes are often accompanied by jaundice and can be accompanied by gastrointestinal symptoms such as nausea, vomiting, and anorexia. According to statistics, cases with abdominal pain symptoms account for about 60-80% of all cases.
2. Mass: Mostly smooth masses are palpated in the right upper abdomen with cystic sensation, the upper boundary is mostly covered by the liver margin, and there may be mild to severe tenderness. Some of the cysts have flap-like folds at the lower end of the common bile duct, which acts as an activating flap, and the cysts become smaller when the contents are discharged, and the jaundice gradually subsides. It has a high reference value for the diagnosis of this disease.
3, jaundice: intermittent jaundice for its characteristics, the appearance of jaundice interval length varies, severe jaundice can be accompanied by skin itching, general discomfort. The appearance and deepening of jaundice indicates poor bile drainage due to distal obstruction of the common bile duct. When the inflammation decreases and the bile drains freely, the jaundice may be relieved or subside. In some children, when the jaundice worsens, the stool becomes lighter or even white clay-like, and the urine is dark yellow. In addition to the main symptoms mentioned above, there may be fever when combined with infection in the cyst, and the temperature may be as high as 38-39 ℃, and nausea and vomiting may be caused by inflammation.
V. Diagnosis
Clinical diagnosis The clinical proportion of those with abdominal pain, jaundice and mass is not high, most cases have combined hepatobiliary and pancreatic system diseases, and the rate of congenital cystic dilatation of bile duct is 2.5%-15%.
With the improvement of imaging diagnosis, the diagnosis rate of congenital cystic dilatation of bile duct has reached 70%-90%, and it is easier to diagnose in children than in adults.
(1) Ultrasound: the diagnosis can be initially obtained. It shows a well-defined hypoechoic area under the liver, and the degree and extent of intrahepatic bile duct dilatation and whether it is combined with bile duct stones can be identified. This method is non-invasive, inexpensive, easy to promote, and should be preferred.
(2) Endoscopic ultrasound (EUS): its probe can be placed closer to the lesion in the stomach through the endoscope, which has a unique role in the diagnosis of bile duct cysts.
(3) X-ray examination: suitable for examination of larger cysts, a soft tissue mass with smooth margins and uniform density is seen in the right upper abdomen, and the stomach and colon are seen to be pushed, the gastric sinus is pushed to the upper left, the duodenal segment is pushed to the right, and the duodenal box is enlarged, but it is more difficult to diagnose cloacal dilatation with its ordinary X-ray examination.
(4) CT examination: It can clarify the degree of dilatation of the common bile duct, its location, the degree of distal stenosis of the common bile duct, the presence of intrahepatic bile duct dilatation, the shape and location of the dilatation, etc., which can help in the selection of the operation.
(5) MRCP (Magnetic Resonance Cholangiopancreaticography): It is a high-tech non-invasive imaging technique that has been applied to clinical practice in the 1990s. High-quality MRI technology can obtain clear pancreaticobiliary duct imaging and can clearly determine whether the combined pancreaticobiliary flow is abnormal. However, sometimes due to technical problems of the operator or poor cooperation of the patient, satisfactory images cannot be obtained.
(6) Retrograde cholangiopancreatography (ERCP): It is the most effective examination method for understanding the bile duct, pancreatic duct and pancreaticobiliary duct union, and can provide an important objective basis for the presence or absence of pancreaticobiliary duct coarctation abnormalities and their types. The diagnostic effect can be better than that of PTC.
(7) Percutaneous hepatic cholangiography (PTC): It can show the site of cystic dilatation of intrahepatic bile ducts and the degree of stenosis of distal and proximal bile ducts. To understand the presence or absence of abnormal merging of the pancreaticobiliary duct and pathological changes in the distal pancreaticobiliary duct. Bile can be taken and bacteriological examination can be performed. This method is best used when ERCP examination fails.
(8) Intraoperative cholangiography: Intraoperative cholangiography is necessary for cases with failed preoperative ERCP examination or unclear MRCP. It can provide a detailed understanding of the pathological pattern of the intrahepatic bile duct and the abnormalities of the distal bile duct and pancreaticobiliary syncope. It is very important to guide the selection of the correct surgical method.
VI. Complications
1, bile duct lesions When the combined flow is abnormal, the pressure in the pancreatic duct is higher than the pressure in the bile duct, so that the activated pancreatic juice flows backward into the bile duct and stagnates with infected bile, leading to various lesions.
(1) High amylase bile: The concentration of amylase can reach 100,000 U. Children within 2 years of age can be below the normal level because their pancreatic cells are immature. At this time, if pancreatic peptidase I and lipase show high values, it suggests pancreatic reflux.
(2) Bile duct dilatation: Dilation of the common bile duct can be cystic or prismatic (cylindrical). The former has a younger age of onset, but can be seen at any age, accounting for 1/4 of the cases within 1 year of age, and about half of them are complicated by intrahepatic bile duct dilatation; the latter mostly develops after 1 year of age, while those within 1 year of age are rare. It is easily detected by ultrasound examination. Abnormal syncope is the main cause of bile duct dilatation, but not the only cause.
(3) Bile duct inflammation: associated with biliary stasis and enzyme activation in reflux pancreatic fluid. It can often cause bile duct infection, pancreatitis, purulent cholangitis, and in severe cases, liver abscess and sepsis. Clinical manifestations may include fever, abdominal pain, jaundice and increased white blood cells, and may be accompanied by hyperamylaseemia.
（Yamaguehi analyzed 1433 cases of congenital cystic dilatation of bile ducts, 80% of which were complicated by gallstones, most of which were gallbladder stones, some of which were combined with intracystic stones, and very few were complicated by pancreatic duct stones. In China, Qian Guangxiang and Huang Zhiqiang reported that 71.4% of congenital cystic dilatation of bile ducts were complicated by bile duct stones, but they were pigment stones. 1/4 of them were located in the intrahepatic bile ducts and no gallbladder stones were seen. The detection rate of gallstones has been reported to be about 3%, but it increases with age, almost all of them are combined with gallstones over 40 years old, and almost all of them are complicated by disease duration >20 years. Gallstones are associated with jaundice, pancreatitis and the development of cancer.
(5) Bile duct obstruction: The disease has varying degrees of distal obstruction. In the long run, it can lead to biliary cirrhosis and portal hypertension.
(6) Bile duct cyst perforation: It may be related to pancreatic enzymes in the reflux pancreatic fluid and often occurs after strenuous activity. It is mostly seen in pediatric patients, and almost always combined with abnormal syncope. Diffuse peritonitis can occur after perforation and can be life-threatening in severe cases. Aseptic biliary ascites is in a better state and jaundice can occur after absorption.
(7) Carcinoma: Since Irwin et al. reported the carcinoma of congenital bile duct cyst in 1944, scholars have reported some medical records, the incidence of which is 2.5%～16.7%, adenocarcinoma is about 77.9%～95%, degenerative carcinoma is 21%, squamous epithelial carcinoma is 9%, undifferentiated carcinoma, adenosquamous carcinoma, chyloma, etc. are occasionally reported. The cause of cystic carcinoma is unknown and may be related to several factors: ① Stones: Todani, after counting the cases of cystic carcinoma, speculated that cystic carcinoma is related to gallstones, but the mechanism is unknown. ②Chronic inflammation: After comparing the cancer rate of common bile duct with that of intrahepatic solitary cyst, Watts concluded that the reason for the high cancer rate of the former is due to the long-term stimulation by bile fluid. The pancreatic fluid has alcohol A of phospholipids and the bile has lecithin broken down into lysolecithin. The long-term repeated stimulation of these substances causes inflammatory, ulcerative and regenerative changes in the cystic epithelium. todani summarized that all of the 49 cystectomy specimens had inflammatory scar tissue and/or duodenal epithelial hyperplasia. flanigan reported that 25% of the cystic carcinomas had cystic inflammatory changes. In 1962, Geonge et al. demonstrated a close chemical relationship between bile acids and the carcinogen methylcholanthrene, and in 1984, Bull extracted a highly carcinogenic mutagen from gallstones of patients with choledochal cysts, which was not present in non-cystic patients. The mutagens are metabolized by bacteria and produce carcinogenic effects. Internal drainage: especially in view of the cases after cystoduodenal anastomosis. todani et al. collected world literature on cystic carcinoma and found that 57.1% of carcinoma cases had internal drainage. flanigan had reported that 50% of carcinoma pathology of common bile duct cysts had internal drainage within 4 years. ⑤ Anatomical anomalies: As already mentioned, Miyano, Babbit, John, and Arima have confirmed the presence of an anomaly of pancreaticobiliary coarctation in the pathology of congenital cystic dilatation of the bile duct by various methods. This abnormality causes reflux of pancreatic juice and stimulates the bile duct epithelium causing intestinal epithelial metaplasia. (6) Primary carcinoma: In 1964, Asbby proposed the idea that carcinoma of the common bile duct cyst is primary. After studying a case in which the tumor was located in the posterior wall of the cyst compressing the bile duct and the opening of the common bile duct was unclear, he concluded that the tumor might have originated in the common bile duct causing obstruction and the congenital weak area of the bile duct was stretched to form the common bile duct cyst. In addition, the pathology of this case reported that the mucosa of its common bile duct was intact, i.e., it was actually a cancer that caused the cyst. This contention needs further confirmation.
Compared with primary cholangiocarcinoma, congenital cholangiocystic carcinoma has the following characteristics: (1) the incidence rate is higher than the latter, 20 times higher than primary cholangiocarcinoma; (2) it occurs more often in young people than in older people, and in the latter it occurs more often in people over 40 years of age; (3) it is more common in women in the former (male to female ratio 1:2.5), and in men in the latter; (4) there is a clear racial tendency in the former, with a higher incidence in Asians.
2.Liver lesions
(1) Liver cirrhosis: it can appear in 1 to 2 months old mothers, mostly associated with combined bile duct atresia and congenital liver fibrosis. Most of them are combined with portal hypertension and have poor prognosis.
(2) Portal hypertension: due to cirrhosis, bile duct cyst compression and abnormal portal vein development.
(3) Hepatic vitamin D deficiency disease: long-term persistent jaundice, reduced intestinal bile, impaired fat absorption, resulting in vitamin A deficiency, vitamin D deficiency disease and osteoporosis.
3. Infection or fever Mostly chronic cholecystitis or liver abscess, and it becomes one of the causes of death.
VII. Treatment of symptoms
Treatment during the seizure period is taken by fasting for 2 to 3 days to reduce the secretion of bile and pancreatic juice and relieve the pressure in the bile duct. Application of antispasmodics to relieve pain, antibiotics for 3 to 5 days to prevent and control infection, and corresponding symptomatic treatment can often achieve symptom relief. In view of its frequent attacks and various complications, prompt surgical treatment is advisable.
Cyst and jejunum Roux-en-Y anastomosis such as cystoduodenal anastomosis, because of more complications, recurrent episodes of cholangitis, anastomotic stenosis, stone formation, etc., later turned to cyst-jejunum Roux-en-Y type anastomosis and design various styles of anti-reflux operation on the intestinal loop, but there is still the problem of pancreaticobiliary coarctation, thus the symptoms of cholangitis or pancreatitis still occur after surgery. However, there is still the problem of pancreaticobiliary cohesion, so that the symptoms of biliary ductitis or pancreatitis still occur after surgery, and even require reoperation, and the occurrence of cystic wall cancer after surgery has been reported repeatedly. Therefore, it is rarely used at present.