title: Clinical differences between mass-forming autoimmune pancreatitis and pancreatic cancer.
abstract: OBJECTIVE
  Autoimmune pancreatitis (AIP) needs to be differentiated from pancreatic cancer (PC). We aimed to clarify the findings specific for AIP by comparing the clinical differences between mass-forming AIP and PC.
  
  
  METHODS
  We retrospectively compared 36 patients with mass-forming AIP and 60 with PC without metastasis regarding clinical, imaging, serological, histological differences and other organ involvement (OOI). We evaluated the sensitivity, specificity and accuracy of these findings for the differential diagnosis between AIP and PC.
  
  
  RESULTS
  The findings 100% specific for AIP were a capsule-like rim on computed tomography (CT), skipped lesion of main pancreatic duct (MPD) on endoscopic retrograde pancreatography (ERP) or magnetic resonance cholangiopancreatography (MRCP), γ-globulin > 2 g/dl, OOI (extrapancreatic biliary stricture, salivary gland swelling and retroperitoneal fibrosis) and ruling out PC by histopathological findings of endoscopic ultrasonography-guided fine-needle aspiration. The findings over 90% specific were IgG4 > 280 mg/dl (98%), IgG > 1800 mg/dl (97%), maximal diameter of upstream MPD < 5 mm on MRCP (95%) and IgG4 > 135 mg/dl (94%), respectively.
  
  
  CONCLUSIONS
  Clinical, imaging, serological, histological findings and OOI differed between mass-forming AIP and PC. Capsule-like rim on CT, skipped lesion of MPD on ERP or MRCP, IgG4 > 280 mg/dl, and OOI were highly specific findings for AIP. These findings are useful in the differential diagnosis of mass-forming AIP from PC.
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Naitoh
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Kazuki
authors.initials: K
authors.lastname: Hayashi
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Okumura
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Miyabe
authors.forename: Shuya
authors.initials: S
authors.lastname: Shimizu
authors.forename: Hiromu
authors.initials: H
authors.lastname: Kondo
authors.forename: Michihiro
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yamashita
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ohara
authors.forename: Takashi
authors.initials: T
authors.lastname: Joh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001649:Bile Duct Diseases / Q000150:complications; D044963:Biopsy, Fine-Needle; D002760:Cholangiopancreatography, Endoscopic Retrograde; D049448:Cholangiopancreatography, Magnetic Resonance; D003251:Constriction, Pathologic / Q000150:complications; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D010183:Pancreatic Ducts / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010195:Pancreatitis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D012185:Retroperitoneal Fibrosis / Q000150:complications; D012189:Retrospective Studies; D012466:Salivary Gland Diseases / Q000150:complications; D014057:Tomography, X-Ray Computed; D005719:gamma-Globulins / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D005719:gamma-Globulins