Precancerous Pyloric Gland Metaplasia in the Biliary Epithelium Associated with Congenital Biliary Dilatation in a Three-Month-Old Infant.

Pyloric gland metaplasia in the biliary epithelium is a precancerous lesion and has been confirmed in patients with congenital biliary dilatation presenting with overt biliary tract cancer. A patient was found to have an intra-abdominal cyst on fetal ultrasonography and was born at 37 weeks of gestation with a body weight of 2,636 g. Abdominal distension and repeated vomiting appeared 2 days after birth. Congenital biliary dilatation was diagnosed by imaging, wherein the common bile duct was enlarged to 9-10 cm in size, and the surrounding organs were extensively compressed; however, there was no sign of pancreatitis or cholangitis. Biliary drainage was performed through the gallbladder at 6 days of age, but it was insufficient because of the narrow and twisted cystic duct and changed to common bile duct at 18 days to relieve the compression. Because the body weight gain was poor due to loss of large amount of bile, the dilated bile duct and gallbladder were resected and hepatic duct Roux-Y jejunostomy was performed at 115 days of age with 4,500 g of body weight. Intraoperative imaging showed a pancreaticobiliary maljunction, and the pancreatic enzyme activities of the bile in the biliary system were remarkably elevated. Histopathological examination revealed pyloric gland metaplasia in the gallbladder epithelium and cystic duct. The patient is now over 2 years old and has been doing well without any complications. Based on our experience, precancerous pyloric gland metaplasia of the biliary epithelium may already occur even in a 3-month-old infant presenting with congenital biliary dilatation.