Unjaundiced preschooler with vomiting and abdominal pain

CT and cholangiogram of choledochal cyst Type I
Axial (above left) and coronal (above right) CT without contrast of the abdomen show a large cystic lesion between the right kidney and pancreas with extensive surrounding inflammation. The gall bladder was normal. AP image from intraoperative cholangiogram (below) shows the lesion represents diffuse dilation of the common bile duct with free passage of contrast into the small bowel.

The diagnosis was choledochal cyst Type I.