title: Endobiliary metastasis from rectal cancer mimicking intrahepatic cholangiocarcinoma: a case report and review of literature.
abstract: OBJECTIVE
  The purpose of this study is to report an unusual case of liver metastasis from carcinoma rectum, which mimicked an intrahepatic cholangiocarcinoma (ICC) radiologically and pathologically, and to review the relevant literature.
  
  
  METHODS
  A 64-year-old gentleman was treated for carcinoma rectum in our institution with neoadjuvant chemoradiation followed by low anterior resection and adjuvant chemotherapy. Two years later, he was found to have a nodule in the left hepatic duct on imaging. He underwent left hepatectomy.
  
  
  RESULTS
  The specimen revealed a tumor in the left hepatic duct, microscopically resembling an ICC. However, immunohistochemistry (IHC) showed the tumor cells to stain positively for cytokeratin 20, but not for cytokeratin 7, thus confirming the metastatic nature of the lesion.
  
  
  CONCLUSIONS
  Endobiliary metastasis from colorectal cancer can mimic ICC, and IHC studies may be needed to differentiate the two. Identifying endobiliary metastasis can have therapeutic and prognostic implications.
authors.affiliation: Department of Surgical Oncology, Cancer Institute (WIA), Annexe Campus, No.18, Sardar Patel Road, Guindy, Chennai 600036, India. ram_a_s@yahoo.com
authors.forename: Ramakrishnan Ayloor
authors.initials: RA
authors.lastname: Seshadri
authors.forename: Urmila
authors.initials: U
authors.lastname: Majhi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000628:therapy; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001650:Bile Duct Neoplasms / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D018281:Cholangiocarcinoma / Q000473:pathology*; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D013505:Digestive System Surgical Procedures; D006801:Humans; D007150:Immunohistochemistry; D053554:Keratin-20 / Q000378:metabolism; D053552:Keratin-7 / Q000378:metabolism; D008113:Liver Neoplasms / Q000556:secondary*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D011878:Radiotherapy; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy
chemical_list: D053554:Keratin-20; D053552:Keratin-7