Common bile duct cyst: causes, symptoms, diagnosis, treatment

A cyst of the common bile duct is its expansion. The gallbladder, cystic duct and hepatic ducts above the cyst are not expanded, unlike strictures, in which the entire biliary tree expands above the stricture. A combination of a cyst of the common bile duct and Caroli's disease is possible. Histological examination shows that the cyst wall is fibrous tissue that does not contain epithelium or smooth muscles. In patients with a cyst of the common bile duct, an anomaly of its fusion with the pancreatic duct (long common segment) has been described. It is assumed that the formation of the cyst is caused by the reflux of pancreatic enzymes into the bile ducts.

Common bile duct cysts are classified as follows:

• Type I - segmental or diffuse fusiform dilatation.
• Type II - diverticulum.
• Type III - choledochocele of the distal part of the common bile duct, predominantly within the wall of the duodenum.
• Type IV - anatomical changes characteristic of type I are combined with a cyst of the intrahepatic bile ducts (IVa; Caroli type) or with a choledochocele (IVb). If type V is distinguished, it is understood as Caroli disease.

The most common form is the fusiform extrahepatic cyst (type I), followed by a combination of intra- and extrahepatic changes (type IVa). There is still no consensus on whether a choledochocele (type III) should be considered a cyst.

Isolated cystic dilation of the intrahepatic bile ducts is occasionally observed.

Type I cyst is detected as a partially retroperitoneal cystic tumor-like formation, the size of which is subject to significant fluctuations: from 2-3 cm to reaching a volume of 8 liters. The cyst contains dark brown fluid. It is sterile, but can become secondarily infected. The cyst can rupture.

In the later stages, the disease may be complicated by biliary cirrhosis. Cysts of the common bile duct may compress the portal vein, leading to portal hypertension. Malignant tumors may develop in the cyst or bile ducts. Biliary papillomatosis with a mutation of the K-ras gene has been described.

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Symptoms of a common bile duct cyst

In infants, the disease manifests itself as prolonged cholestasis. Perforation of the cyst with the development of bile peritonitis is possible. In older children and adults, the disease usually manifests itself as transient episodes of jaundice, pain against the background of a volumetric formation in the abdomen. In children more often than in adults (in 82 and 25% of cases, respectively), at least two signs of this "classic" triad are noted. Although the disease was previously classified as a childhood disease, it is now more often diagnosed in adults. In a quarter of cases, the first manifestations are symptoms of pancreatitis. Cysts of the common bile duct more often develop in the Japanese and other Eastern peoples.

Jaundice is intermittent, cholestatic, and accompanied by fever. The pain is colicky, localized mainly in the right upper quadrant of the abdomen. The mass is caused by a cyst, is detected in the right upper quadrant of the abdomen, and has different sizes and densities.

Cysts of the common bile duct may be associated with congenital liver fibrosis or Caroli's disease. Disturbances in the drainage of bile and pancreatic secretions are of great importance, especially if the ducts join at a right or acute angle.

Microhamartoma (von Meyenberg complexes)

Microhamartomas are usually not clinically evident and are detected by chance or at autopsy. Rarely, they may be associated with portal hypertension. Microhamartoma may be associated with medullary spongy kidneys, as well as polycystic kidney disease.

Histologically, microhamartoma consists of a cluster of bile ducts lined with cuboidal epithelium, often containing thickened bile in their lumen. These biliary structures are surrounded by a stroma composed of mature collagen. They are usually located within or near portal tracts. The histological picture resembles congenital liver fibrosis, but has a localized character.

Visualization methods

On liver arteriograms with multiple microhamartomas, the arteries appear stretched, and the vascular pattern in the venous phase is enhanced.

Carcinoma as a complication of polycystic disease

Tumors can develop with microhamartomas, congenital liver fibrosis, Caroli disease, and common bile duct cysts. Carcinoma rarely develops with nonparasitic cysts and polycystic liver disease. The probability of malignant transformation increases in areas where the epithelium contacts bile.

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Diagnosis of common bile duct cyst

Plain abdominal radiography reveals a soft tissue mass. In infants, an iminodiacetate scan or ultrasound may sometimes reveal a cyst in utero or postpartum. In older children and adults, the cyst is detected by ultrasound or CT. All diagnostic methods may yield false negative results. The diagnosis is confirmed by percutaneous or endoscopic cholangiography.

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Treatment of common bile duct cyst

Due to the risk of developing adenocarcinoma or squamous cell carcinoma, excision of the cyst is the method of choice. Bile drainage is restored by choledochojejunostomy with anastomosis with a Roux-en-Y loop of intestine.

Anastomosis of the cyst with the intestine without its excision is simpler, but cholangitis often develops after the operation, and subsequently duct strictures and stones are formed. The risk of developing carcinoma, possibly associated with dysplasia and metaplasia of the epithelium, remains.