Choledochal cyst rupture with an intrahepatic pseudocyst mimicking hepatic mesenchymal hamartoma in an infant.

Spontaneous choledochal cyst rupture and consequent biliary peritonitis are rare in children. Here, we report a unique case of intrahepatic bile duct rupture of choledochal cyst type IV that resulted in loculated biliary peritonitis with an intrahepatic pseudocyst mimicking a hepatic mesenchymal hamartoma in a 3-month-old boy. Magnetic resonance cholangiopancreatography can help differentiate these conditions. Regardless of the location, pseudocysts resulting from biliary peritonitis should be considered in cases of choledochal cysts with adjacent fluid collection or cystic lesions.