Caroli disease and choledochal cysts

Diagnostic Imaging of Caroli Disease

Caroli disease (Caroli disease) is based on a structural anomaly of the intrahepatic ducts. In the classification of biliary tract malformations, this condition is classified as a type 5 choledochal cyst.

Ultrasound is the primary initial imaging modality. A key marker that raises suspicion for the diagnosis is the “central dot sign” (central dot sign). It represents a branch of the portal vein surrounded on all sides by the lumen of a pathologically dilated bile duct.

When such an echographic pattern is identified, differential diagnosis with sclerosing or recurrent pyogenic cholangitis must be performed. The main danger of Caroli disease lies in complications caused by chronic bile stasis. These include recurrent infectious cholangitis, stone formation (biliary obstruction), and the development of secondary liver cirrhosis. Furthermore, in adult patients, the risk of developing a malignant tumor—cholangiocarcinoma—significantly increases. The standard treatment for this pathology is surgical (most frequently hepatopancreatoenterostomy).

Inspissated Bile Syndrome and Gallstone Formation

In infants and young children, symptoms of obstructive jaundice are often caused not by true cysts, but by inspissated bile syndrome (Inspissated Bile). This condition is closely associated with prematurity, hemolytic disorders, total parenteral nutrition, cystic fibrosis (CF), and functional intestinal obstruction (e.g., Hirschsprung's disease). In infants, the syndrome is often idiopathic in nature.

• Ultrasound appearance: Mildly echogenic bile without acoustic shadowing is visualized within the lumen of the gallbladder and ducts. Secondary dilation of the biliary tree (predominantly extrahepatic) is observed. If the condition persists chronically, the echogenicity of periportal tissues increases.
• Differential diagnosis: In infants, the clinical picture requires the exclusion of choledochal malformations (cysts).

The transition from biliary sludge to the formation of true hard stones does not always occur. Gallstones in children are generally extremely rare in the absence of provoking risk factors: obesity, small bowel pathology, hemolysis, or anatomical defects of the choledochus.

Sclerosing Cholangitis and Other Ductal Disorders

The development of cholangitis in children always requires a thorough investigation for predisposing factors (anatomical anomalies, congenital hepatic fibrosis, stones, or post-transplant complications). Sclerosing cholangitis occupies a special place among them.

The imaging findings of this disease in children are similar to those in adult patients: cholangiograms or MRCP reveal a “beaded appearance” (beaded appearance). This effect occurs due to multiple alternating strictures and dilations of both the intrahepatic and extrahepatic bile ducts.

1. Primary Sclerosing Cholangitis (PSC): Diagnosed in 80% of patients with concomitant ulcerative colitis (inflammatory bowel disease is found in half of children with PSC). Clinical symptoms usually onset after 2 years of age.
2. Secondary Sclerosing Cholangitis: May be a manifestation of Langerhans cell histiocytosis.

The pathology leads to progressive intrahepatic cholestasis and irreversible cirrhosis. The risk of malignant transformation with the development of cholangiocarcinoma reaches 0.6–1.5% annually. However, it should be noted that the development of cholangiocarcinoma directly from choledochal cysts in childhood is unlikely.

Associated Pancreatic Anomalies

When evaluating the biliary system, the pancreatobiliary junction zone is always assessed. Visualization of the pancreas in children is usually easily performed using ultrasound (the tail of the pancreas is well visualized through the splenic acoustic window). Normal dimensions of the head and tail are 1–2 cm, the body is 0.6–1.1 cm, and the duct diameter varies from 1.1 mm in infants to 2.1 mm in adolescents.

The most significant congenital anomalies of the organ:

• Pancreas divisum (Pancreas Divisum): Occurs due to the failure of fusion of the ventral and dorsal embryonic buds. The smaller ventral bud takes over the formation of the bulk of the gland. Drainage occurs via the minor duodenal papilla through the duct of Santorini.
• Annular pancreas (Annular Pancreas): The pancreatic tissue forms a ring encircling the descending part of the duodenum, causing obstruction. Neonatal radiographs reveal a characteristic double-bubble sign. In 71% of infants, this anomaly is associated with other malformations, notably Down syndrome (trisomy 21).

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Persistent intrahepatic cholestasis and Alagille syndrome
• Spontaneous bile duct perforation in infants (the role of scintigraphy)
• Biliary rhabdomyosarcoma and porta hepatis mass lesions
• Dorsal pancreatic agenesis and its association with diabetes mellitus
• Ectopic pancreatic tissue (stomach, small intestine)

Other Topics in "Pediatric Diagnostic Radiology"

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