title: Clinicopathological Meaning of Size of Main-Duct Dilatation in Intraductal Papillary Mucinous Neoplasm of Pancreas: Proposal of a Simplified Morphological Classification Based on the Investigation on the Size of Main Pancreatic Duct.
abstract: BACKGROUND
  The 2012 consensus guideline on intraductal papillary mucinous neoplasm of the pancreas (IPMN) described a three-stage criteria involving main pancreatic duct (MPD) size with definitions of malignancy relevant for treatment decisions. Re-evaluation and simplification of this classification for clinicians are warranted.
  
  
  METHODS
  Data from the Seoul National University Hospital of 375 consecutive patients with pathology-confirmed IPMN after surgery were analyzed. The association between clinicopathologic characteristics of IPMN and MPD size was assessed. The cut-off value of MPD size for a current definition of malignancy prediction was calculated.
  
  
  RESULTS
  Diagnostic accuracy for malignancy was highest when the cut-off value of MPD size was 7 mm (area under the curve=0.7126). Dichotomizing IPMN into MPD≤7 mm versus MPD> mm, patient age (p=0.039), sex (p=0.001), presence of mural nodule (p<0.001), and invasiveness risk (13.2 vs. 39.8%, p<0.001) resulted in significantly different results. Mural nodule-negative patients with MPD>7 mm had a significantly lower 5-year survival rate than those with MPD≤7 mm (78.4 vs. 91.4%, p=0.006). Among patients with MPD size≤7 mm, elevated serum CA 19-9 and mural nodule were independent risk factors of malignancy. Patients with MPD size≤7 mm without these risk factors had malignancy risk of 2.6%.
  
  
  CONCLUSIONS
  Using the definition of malignancy provided in the 2012 guideline, the MPD size> mm criterion was statistically driven. The current morphologic classification of IPMN can be simplified as branch-duct-predominant IPMN (MPD≤7 mm)' and main-duct-predominant IPMN (MPD> mm). Patients who are determined to have main-duct-predominant IPMN and branch-duct-predominant IPMN with elevated serum CA 19-9 or mural nodule are recommended to undergo surgical treatment.
authors.affiliation: Department of Surgery and Cancer Research Institute, Seoul National University College of Medicine, 101 Daehak-ro, Chongno-gu, Seoul, 110-744, South Korea, meejookang@gmail.com.
authors.forename: Mee Joo
authors.initials: MJ
authors.lastname: Kang
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Jang
authors.forename: Selyeong
authors.initials: S
authors.lastname: Lee
authors.forename: Taesung
authors.initials: T
authors.lastname: Park
authors.forename: Seung Yeoun
authors.initials: SY
authors.lastname: Lee
authors.forename: Sun-Whe
authors.initials: SW
authors.lastname: Kim
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis* / Q000401:mortality / Q000601:surgery; D000368:Aged; D018395:CA-19-9 Antigen / Q000097:blood; D021441:Carcinoma, Pancreatic Ductal / Q000175:diagnosis* / Q000401:mortality / Q000601:surgery; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000401:mortality / Q000601:surgery; D049448:Cholangiopancreatography, Magnetic Resonance; D004108:Dilatation, Pathologic; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D010183:Pancreatic Ducts / Q000000981:diagnostic imaging / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000601:surgery; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014057:Tomography, X-Ray Computed
chemical_list: D018395:CA-19-9 Antigen