title: Periductal infiltrating type of intrahepatic cholangiocarcinoma: a rare macroscopic type without any apparent mass.
abstract: OBJECTIVE
  This study was undertaken to elucidate the clinicopathological characteristics and surgical outcome of the periductal infiltrating (PI) type of intrahepatic cholangiocarcinoma (ICC), which is a distinct macroscopic type of ICC arising from the second-order of the intrahepatic bile ducts without apparent invasion of the surrounding liver parenchyma.
  
  
  METHODS
  All patients with the PI type of ICC were identified from a database of patients with intrahepatic cholangiocellular carcinoma that underwent surgical resection between 1983 and 2009. The clinicopathological data of these patients were analyzed retrospectively.
  
  
  RESULTS
  Sixteen of 203 patients (7.9%) had the PI type of ICC. The median survival was 7.7 years with 5-year survival rate of 62.1%. The PI type of ICC showed a significantly better survival than the mass-forming (MF) type (P = 0.0293) or MF plus PI type of ICC (P = 0.0001). Microscopic examinations showed intrahepatic metastasis to be absent in all the patients with PI type ICC. The incidence of intrahepatic metastases in patients with PI type was significantly lower in comparison to that of patients with MF type (P = 0.0030) and MF plus PI type (P = 0.0533), respectively.
  
  
  CONCLUSIONS
  Surgery could therefore provide a favorable outcome in patients with the PI type of ICC, probably due to its lower incidence of intrahepatic metastases.
authors.affiliation: Hepatobiliary and Pancreatic Surgery Division, National Cancer Center Hospital, 5-1-1Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Uno
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Shimada
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nara
authors.forename: Minoru
authors.initials: M
authors.lastname: Esaki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Tomoo
authors.initials: T
authors.lastname: Kosuge
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ojima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001650:Bile Duct Neoplasms; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000401:mortality / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D005260:Female; D006498:Hepatectomy; D006801:Humans; D008113:Liver Neoplasms / Q000401:mortality / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome