A new variant of Todani type I choledochal cyst. Imaging evaluation

Choledochal cysts are congenital segmental aneurysmal dilatations of any portion of bile ducts, most commonly of the main portion of the common bile duct. The classification system of choledochal cysts is based on the site of the cyst or dilatation and currently includes 5 major types. The purpose of our study is to describe the imaging findings of a new variant of choledochal cyst.

Six patients (4 children and 2 adults, 4 females and 2 males, 3-67 year old) were evaluated by US, CT, CT-cholangiography, MRI, magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP), because of jaundice, abdominal pain and a palpable mass.

A new type of choledochal cyst was demonstrated in all cases. In this new variant apart from the dilatation of the common hepatic and the common bile duct, dilatation of the central portion of the cystic duct was also observed, giving a bicornal configuration to the cyst.

The imaging findings of a new variant of choledochal cyst with participation of the cystic duct are described. We propose the classification of this type of choledochal cyst as a new subtype of Todani I cyst, namely Todani ID.