Spontaneous perforation of choledochal cyst: a case with unusual distribution of fluid in the retroperitoneal space.

Images of perforated choledochal cysts typically show an intraperitoneal fluid collection. We report a case with, in addition to free intraperitoneal fluid, fluid collection in the right-side anterior pararenal and perirenal spaces. Surgery confirmed the presence of a perforation at the junction of the cystic duct and the common bile duct. This perforation may explain the biliary leakage extending into the free peritoneal space as well as into the anterior pararenal space and the hepatoduodenal ligament. Anterior pararenal and perirenal spaces communicate with the infrarenal space, and this may result in extension of the fluid into the perirenal space from the anterior pararenal space.