Is that you, choledochal cyst?

Clinical History

A 73-year-old woman presented in our institution with right upper quadrant pain, nauseas and vomiting episodes that didn't respond to symptomatic treatment. Analytically, AST, ALT and GGT were elevated.

Imaging Findings

An ultrasound was performed showing a cystic formation in the right upper abdominal quadrant, in apparent communication with the common bile duct (CBD). For a better characterization a magnetic resonance cholangiopancreatography was performed. The presence of a diverticular cystic formation in communication with the CBD was confirmed. It presented with lobular contours and a size of 37 mm. Both the CBD and pancreatic duct (PD) presented with normal calibre and the pancreatic parenchyma showed normal signal characteristics on MRI.

Discussion

Choledochal cysts (CD) constitute a rare congenital anomaly characterized by an uneven dilatation of the intra or extra-hepatic biliary tract. With a higher prevalence in Asia, women are more frequently affected (1 men: 4 women) [1].
The aetiology of CD is unclear and multiple theories exist, anomalous union of the CBD and PD being the more consensual and believed to cause weakening of the CBD by the abnormal presence of pancreatic enzymes entering the biliary tract [2].
Clinical manifestations include abdominal pain, fever and palpable abdominal mass and more specific symptoms such as cholangitis and jaundice [3].
Two types of classifications are used to define this anomaly, one based on the angle of CBD union with the PD, Komi classification, and another based on the cholangiographic morphology, location, and number of intrahepatic and extrahepatic bile duct cysts, Todani classification [2].
Todani divides them in five types [4]:
Type I – The most common type, refers to cysts confined to the CBD in a diffuse and saccular manner (type Ia) or focal manner (type 1b). Type Ic refers to a fusiform dilatation of the CBD.
Type II – Correspond to true diverticula of the CBD and are the rarest (2%). They also are a potential pitfall for gallbladder duplication.
Type III – Cysts that are formed in intramural segment of the distal common bile duct, also known as choledochoceles.
Type IV – Multiple cystic dilatations that can involve both the intra and extra-hepatic ducts (type IVA) or only affect the extra-hepatic ducts (type 4b).
Type V – also referred as Caroli syndrome, corresponds to segmental cystic dilatation of the intrahepatic biliary ducts.
The imaging features include cystic structures with a saccular or fusiform morphology that have a clear communication to the biliary ducts. Although endoscopic retrograde cholangiopancreatography is regarded as the gold standard for the diagnosis of CD, due to its inherent morbidity, magnetic resonance cholangiopancreatography is usually the method of choice for this entity because it is a radiation-free and non-invasive technique that also allows excellent depiction of the biliary tract [5].
In terms of complications, the most frequent are cholecystitis, recurrent cholangitis, gallbladder stone formation, recurrent acute pancreatitis and malignant transformation into cholangiocarcinoma [6].
Treatment options are usually surgical with complete excision of the extra-hepatic duct, cholecystectomy, and Roux-en-Y hepaticojejunostomy [2].
Choledochal cysts in adults are a rare finding and should be kept in mind as a differential diagnosis for cystic lesions of the biliary tract, regardless of the patient's age.

Differential Diagnosis List

Final Diagnosis

Type II choledochal cyst (Todani classification)

URL:	https://www.eurorad.org/case/14084
DOI:	10.1594/EURORAD/CASE.14084
ISSN:	1563-4086