title: Localized type 1 autoimmune pancreatitis superimposed upon preexisting intraductal papillary mucinous neoplasms.
abstract: A 70-year-old woman was found to have 2 cystic lesions in the head of the pancreas on abdominal ultrasonography during a routine medical examination. Endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography showed multilocular cysts in the head of the pancreas without dilation of the main pancreatic duct. The patient was followed-up semiannually with imaging studies for suspected branch duct-type intraductal papillary mucinous neoplasm (IPMN). At 3 years after initial presentation, hypoechoic lesions were observed around each pancreatic cyst by EUS. Diffusion-weighted imaging showed high-intensity regions corresponding to these lesions. Therefore, a diagnosis of invasive carcinoma derived from IPMN could not be excluded, and subtotal stomach-preserving pancreaticoduodenectomy was performed. The macroscopic examination of the surgical specimen showed whitish solid masses in the head of the pancreas, with multilocular cysts within each mass. Microscopically, each solid mass consisted of inflammatory cells such as lymphocytes and plasma cells. Furthermore, immunochemical staining revealed immunoglobulin G4-positive cells, and many obliterating phlebitides were observed. The cysts consisted of mucus-producing epithelial cells and showed a papillary growth pattern. Based on these findings, we diagnosed multiple localized type 1 autoimmune pancreatitis occurring only in the vicinity of the branch duct-type IPMN.
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Urata
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Naito
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Yoshi
authors.initials: Y
authors.lastname: Takekuma
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokomizo
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Nagamine
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Notohara
authors.affiliation: Takahiro Urata, Yoshihiro Izumi, Yoshi Takekuma, Michio Hifumi, Department of Gastroenterology, Japanese Red Cross Kumamoto Hospital, Kumamoto 861-8520, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Hifumi
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D001706:Biopsy; D021441:Carcinoma, Pancreatic Ductal / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D049448:Cholangiopancreatography, Magnetic Resonance; D038524:Diffusion Magnetic Resonance Imaging; D019160:Endosonography; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D018297:Neoplasms, Cystic, Mucinous, and Serous / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D010181:Pancreatic Cyst / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D016577:Pancreaticoduodenectomy; D010195:Pancreatitis / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D016896:Treatment Outcome
keywords: Autoimmune pancreatitis; Diffusion-weighted imaging; Endoscopic ultrasonography; Immunoglobulin G4; Intraductal papillary mucinous neoplasm