title: Presence of Cytokeratin 19-Expressing Cholangiocarcinoma-Like Tumour in a Liver Metastatic Lesion of Rectal Neuroendocrine Tumour.
abstract: BACKGROUND
  Tumours with adenocarcinoma and neuroendocrine components have often been reported, although the reason underlying the dual components remains unclear.
  
  
  METHODS
  A 43-year-old woman with multiple liver metastatic lesions of rectal neuroendocrine tumour underwent primary tumour resection and subsequent liver transplantation. Pathological examination indicated a cholangiocarcinoma-like tumour with gland formation, adjacent to a liver metastatic lesion of the neuroendocrine tumour. This tumour comprised atypical columnar epithelium, and stained positively for neuroendocrine markers and the ductal marker cytokeratin 19, indicating amphicrine properties and a partial cholangiocarcinoma phenotype - features not observed in the primary and metastatic neuroendocrine tumours.
  
  
  CONCLUSIONS
  The presence of adenocarcinoma only at the metastatic site indicated that neuroendocrine tumour cells acquired stemness and differentiated into adenocarcinoma through metastasis, or that the adenocarcinoma newly arose from the adjacent epithelium influenced by the neuroendocrine tumour. We propose a novel mechanism for the pathogenesis of mixed tumours in neuroendocrine tumours.
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan; Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Ishii
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan; Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Araki
authors.affiliation: Department of Molecular Pharmacology and Oncology, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yokobori
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan; Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Tsukagoshi
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Igarashi
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan; Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan; Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Kubo
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Hirai
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Shirabe
authors.affiliation: Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kuwano
keywords: Adenocarcinoma; Amphicrine tumour; Bile duct; Carcinogenesis; Mixed adenoneuroendocrine carcinoma; Stem cell