Congenital choledochal cyst opening into the intraduodenal part of the common bile duct and complicated by cystolithiasis and acute pancreatitis.

The aim of this report was to present an interesting surgically treated patient having a rare type III choledochal cyst with peculiar clinical course. Anatomically the cyst was a diverticulum of ampulla Vater. It contained stones and was lined by duodenal mucosa. At admission the patient had an actual, severe pancreatitis simulating appendicitis. Two laparotomies were done before the final successful cystoduodenostomy. Ultrasonography was the most illustrative and reliable preoperative diagnostic method.