title: Cyst size indicates malignant transformation in branch duct intraductal papillary mucinous neoplasm of the pancreas without mural nodules.
abstract: OBJECTIVE
  In branch duct intraductal papillary mucinous neoplasm (IPMN) of the pancreas, the importance of the cyst size to predict malignancy is still controversial. Our aim was to elucidate the malignant potential of branch duct IPMN without mural nodules (flat branch duct IPMN).
  
  
  METHODS
  Seventy-three patients with flat branch duct IPMNs were studied in our institution.
  
  
  RESULTS
  There were 6 malignant IPMNs in this series, all of which were 30 mm or more in size, whereas there was no malignancy in IPMNs of less than 30 mm. Statistically significant predictors of malignancy were atypical cytological condition and main pancreatic duct (MPD) diameter of 5 mm or more. The cyst size of 30 mm or more tended to be associated with malignancy. The frequency of malignancy in flat branch duct IPMNs with the size of 30 mm or more and MPD diameter of less than 5 mm was 3.6%, whereas there were 5 malignant cases (26.3%) in flat branch duct IPMNs with the size of 30 mm or more and MPD diameter of 5 mm or more.
  
  
  CONCLUSIONS
  We conclude that the size criteria (> or =30 mm) to predict malignancy proposed in the international consensus guidelines is appropriate and resection or meticulous follow-up using cytological examination and MPD dilatation is needed in patients with flat branch duct IPMNs.
authors.affiliation: Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Sadakari
authors.forename: Jun
authors.initials: J
authors.lastname: Ienaga
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Miyasaka
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takahata
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Mizumoto
authors.forename: Masao
authors.initials: M
authors.lastname: Tanaka
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology* / Q000601:surgery; D000231:Adenocarcinoma, Papillary / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology* / Q000601:surgery; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D016017:Odds Ratio; D010181:Pancreatic Cyst / Q000473:pathology* / Q000601:surgery; D010183:Pancreatic Ducts / Q000473:pathology* / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000473:pathology* / Q000601:surgery; D011230:Precancerous Conditions / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors