title: Mode of progression of intraductal papillary-mucinous tumor of the pancreas: analysis of patients with follow-up by EUS.
abstract: BACKGROUND
  We investigated the mode of progression of intraductal papillary-mucinous neoplasm of the pancreas (IPMN) in patients who underwent follow-up in order to elucidate the characteristics of malignancy and to establish an effective treatment strategy.
  
  
  METHODS
  Fifty-one patients with IPMN (branch-duct type, 47; main-duct type, 4) who had undergone follow-up study by endoscopic ultrasonography (EUS) were included (mean follow-up duration, 41.0+/-32.3 months; average number of EUS examinations performed during follow-up, 4.4). Chronological changes in EUS findings and histological findings of resected specimens were evaluated.
  
  
  RESULTS
  Of the patients with the branch-duct type, only 2% showed enlargement of the dilated branches. In the main-duct-type group, an increase in size of the main pancreatic duct (MPD) was observed in 75% of the patients. In 14 patients with papillary protrusions, an increase in size and lateral spread was observed in 71% and 43%, respectively. No patients developed invasive cancer. In 15 patients who had thick septum-like structures (TSS), the development of papillary protrusions and that of invasive cancer were observed in 53% and 13%, respectively. Twenty-nine patients who had thin septum-like structures showed no change. Two patients with dense multilocular large cysts and TSS developed invasive cancer without change in the cystic lesions. One patient developed carcinoma with multifocal stromal invasion.
  
  
  CONCLUSIONS
  Patients with branch-duct type IPMNs without papillary protrusions or TSS are not immediate candidates for surgery. Those who have small papillary protrusions have a benign course. It is recommended that patients with the large branch-duct type with TSS should undergo surgery. Attention should be paid to the entire pancreas when performing follow-up examinations in patients with branch-duct type IPMN, as invasive ductal adenocarcinoma can develop at a site in the pancreas different from that of the IPMN.
authors.affiliation: Department of Gastroenterology, Sendai City Medical Center, 5-22-1 Tsurugaya, Miyagino-ku, Sendai, 983-0824, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Kobayashi
authors.forename: Naotaka
authors.initials: N
authors.lastname: Fujita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Noda
authors.forename: Kei
authors.initials: K
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Horaguchi
authors.forename: Osamu
authors.initials: O
authors.lastname: Takasawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Akaishi
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Masao
authors.initials: M
authors.lastname: Kobari
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D001707:Biopsy, Needle; D021441:Carcinoma, Pancreatic Ductal / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000379:methods; D015331:Cohort Studies; D018450:Disease Progression; D019160:Endosonography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009367:Neoplasm Staging; D010180:Pancreatectomy / Q000379:methods; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D012189:Retrospective Studies; D018570:Risk Assessment