Pancreatic pseudocyst arising from ectopic pancreas and isolated intestinal duplication in mesocolon caused hydronephrosis in a girl with horseshoe kidney.

Ectopic pancreas is a relatively common congenital anomaly and is usually asymptomatic. Pancreatitis in the ectopic site and pseudocyst formation is extremely rare. To date, only 2 cases have been reported. We present a case of a 3-year-old girl with recurrent pancreatitis and unilateral hydronephrosis of the horseshoe kidney, which was produced by pancreatic pseudocyst arising from ectopic pancreas and isolated intestinal duplication in mesocolon. This is the first case of pancreatic pseudocyst that expanded to the retroperitoneal space and caused urinary tract obstruction.