A santorinicele is defined as a focal cystic dilatation of the terminal portion of the dorsal pancreatic duct at the minor papilla; most cases have been reported in patients with pancreas divisum. It has been suggested that a santorinicele results from a combination of a minor papilla obstruction which prevents the flow of pancreatic juice and a weakness of the duodenal wall where the dorsal pancreatic duct terminates. However, these conditions can occur in patients with invasive ductal cancer in the pancreatic head. We encountered a rare case of a santorinicele with unresectable adenocarcinoma of the pancreatic head in an 81-year-old woman.