Coexistence of mucinous cystic neoplasm occurring in the head of the pancreas with annular pancreas: report of a case.

Mucinous cystic neoplasms (MCN) of the pancreas are rare tumors that are almost exclusively located in the body or the tail of the pancreas. A 60-year-old woman with no history of pancreatic disease was referred to our hospital with a chief complaint of dull pain in the upper abdomen. Abdominal computed tomography showed a multilocular cystic mass of 7.0 cm in the head of the pancreas, and endoscopic retrograde cholangiopancreatography showed no communication between the cystic mass and the main pancreatic duct. A pancreatoduodenectomy was performed for the complete resection of the tumor, and an annular pancreas was discovered by accident. The pathological examination of the tumor led to a definitive diagnosis of MCN with ovarian-type stroma. To our knowledge this is the first documented case of MCN occurring in the head of the pancreas and associated with annular pancreas.