Answer: Para-ampullary duodenal wall cyst

Histology: This gross photograph reveals two large cysts in the “groove” area of the pancreas (between the common bile duct, the duodenum and the accessory ampulla). In addition, the background pancreas shows severe chronic pancreatitis with numerous calculi.

Discussion: Para-ampullary duodenal wall cysts are non neoplastic cystic dilatations of the pancreatic ducts in the submucosal pancreatic tissue associated with remnants of the minor papilla. They are associated with pancreatitis and arise in the region of the pancreas between the superior aspect of the head of the pancreas, the bile duct, the duodenum, and the minor papilla, the so called “groove” region. On light microscopy they are lined by a thin, often partially denuded epithelium. In some case a striking reactive spindle cell proliferation can be present. The differential diagnosis, as in this case, would include an intraductal papillary mucinous neoplasm. Intraductal papillary mucinous neoplasms, in contrast to para-ampullary duodenum wall cysts, are lined by a tall columnar mucin producing epithelium.

Para-ampullary duodenal wall cysts are believed to arise from local obstruction and secondary cystic dilatation of the ducts associated with the minor ampulla. This is a non neoplastic entity and the treatment is usually surgical resection.