title: Histological Changes in the Bile Duct after Long-Term Placement of a Fully Covered Self-Expandable Metal Stent within a Common Bile Duct: A Canine Study.
abstract: OBJECTIVE
  To date, it has been difficult to determine the optimal stenting duration of a fully covered self-expandable metal stent (FCSEMS) in a benign biliary stricture. The purpose of this study was to identify the histopathological changes in a bile duct resulting from long-term placement of a FCSEMS.
  
  
  METHODS
  An FCSEMS was inserted into the common bile duct of 12 canines, and the animals were divided into four groups. Posteuthanasia, necropsy was performed to examine the histopathological changes in the bile ducts after 1, 3, 6, and 9 months.
  
  
  RESULTS
  The results of necropsy showed that the covered membranes of the FCSEMSs were intact and easily removed from the bile ducts in 11 of the canines. Severe epithelial hyperplasia of the stented bile duct and epithelial ingrowth into the stent occurred in one animal (from the 3-month group). On histopathological examination, mild inflammatory changes were observed in the stented bile ducts, and there was no significant difference between the four groups. Among the 12 animals, five had de novo stricture.
  
  
  CONCLUSIONS
  An FCSEMS can be inserted into the bile duct without severe histopathological changes up until 9 months. However, a de novo stricture and severe epithelial hyperplasia relating to the stent insertion might occur.
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sang Soo
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
authors.forename: Tae Jun
authors.initials: TJ
authors.lastname: Song
authors.affiliation: Department of Pathology, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
authors.forename: Mee
authors.initials: M
authors.lastname: Joo
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Do Hyun
authors.initials: DH
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Dong Wan
authors.initials: DW
authors.lastname: Seo
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sung Koo
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Myung-Hwan
authors.initials: MH
authors.lastname: Kim
keywords: Cholangiopancreatography, endoscopic retrograde; Common bile duct; Common bile duct disease; Dogs; Stents