title: A case of focal autoimmune pancreatitis (AIP) mimicking an intraductal papillary mucinous neoplasm (IPMN).
abstract: The present case involved a 76-year-old man with a cystic mass in the head of his pancreas. The cystic lesion, which measured 17.7 × 9.8 mm, was first detected by ultrasonography (US) at the age of 72 years. Follow-up endoscopic ultrasonography (EUS) performed at 4 years after the lesion had first been detected revealed a mural nodule measuring 14.0 × 8.4 mm in the cyst. Endoscopic retrograde pancreatography (ERP) imaging revealed that the main pancreatic duct was in communication with the cyst and that there was no irregular narrowing of the main pancreatic duct. On the basis of these results, the patient was diagnosed with an intraductal papillary mucinous neoplasm (IPMN), and stomach-preserving pancreaticoduodenectomy was performed. A histopathological examination revealed that the interior of the cystic part of the lesion was lined by a pancreatic ductal epithelium. A pathological examination of the nodular lesion detected storiform fibrosis, severe lymphoplasmacytic infiltration, and hyperplasia in the pancreatic duct epithelium together with a small amount of mucus. On immunohistological staining, the infiltrating lymphoplasmacytes were found to be positive for IgG4. Accordingly, the patient was diagnosed with focal autoimmune pancreatitis (AIP). In conclusion, we reported a case of focal AIP mimicking IPMN. This case showed neither enlargement of the pancreas nor irregular narrowing of the main pancreatic duct.
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan. nakajisou1978@yahoo.co.jp.
authors.forename: So
authors.initials: S
authors.lastname: Nakaji
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Nobuto
authors.initials: N
authors.lastname: Hirata
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujii
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Iwaki
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Shiratori
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakasugi
authors.affiliation: Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Ishii
authors.affiliation: Department of Anatomic Pathology, Kameda Medical Center, Kamogawa, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takeyama
authors.affiliation: Department of Anatomic Pathology, Kameda Medical Center, Kamogawa, Japan.
authors.forename: Kazuei
authors.initials: K
authors.lastname: Hoshi
keywords: Autoimmune pancreatitis; Intraductal papillary mucinous neoplasm; Pancreatic cyst