title: Colon cancer metastasis mimicking intraductal papillary neoplasm of the extra-hepatic bile duct.
abstract: BACKGROUND
  An accurate diagnosis of the primary cancer in cases with metastatic lesions is quite important because misdiagnosis may lead to the selection of incorrect adjuvant therapy and worse long-term outcomes after surgery. The metastatic sites associated with the dissemination of colon cancer are well known and normally predictable, which includes the lymphatic, haematogenous, or peritoneal regions, while other locations are quite rare.
  
  
  METHODS
  In this report, we present a case of colon cancer with an unusual metastatic pattern mimicking an intraductal papillary neoplasm of the bile duct (IPNB) present in the extra-hepatic bile duct with a cytokeratin (CK)-7-negative and CK-20-positive profile (intestinal type).
  
  
  CONCLUSIONS
  In the case of this patient who had a history of colon cancer, immunohistochemical staining for the CKs was useful for distinguishing between primary IPNB and colon cancer metastases. We suspect that the metastatic pattern of this case of colon cancer that mimicked IPNB at the extra-hepatic bile duct developed incidentally via the bile stream.
  
  
  CONCLUSIONS
  This is a rare case of colon cancer metastasis mimicking IPNB at the extra-hepatic bile duct. Our findings also suggest that there may be an incidental 4th metastatic route via the bile stream.
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Yamao
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Hayashi
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Higashi
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takeyama
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kaida
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Nitta
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hashimoto
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Chikamoto
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Beppu
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Life Sciences, Kumamoto University, Kumamoto, 1-1-1 Honjo, Kumamoto 860-8556, Japan. Electronic address: hdobaba@kumamoto-u.ac.jp.
authors.forename: Hideo
authors.initials: H
authors.lastname: Baba
keywords: Colon cancer metastasis; Cytokeratin-20; Intraductal papillary neoplasm of the bile duct
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