title: Intrahepatic cholangiocarcinomas mimicking other lesions.
abstract: BACKGROUND
  While the typical features of large cholangiocarcinomas have been described extensively and are known to radiologists, atypical cholangiocarcinomas are not as well known and radiologists should be more aware of their features. Due to the increasing numbers of cross-sectional imaging studies performed for various reasons, cholangiocarcinomas may be more frequently detected incidentally when small, before they become symptomatic, and might be mistaken for other liver lesions. We studied the appearance of misdiagnosed cholangiocarcinomas.
  
  
  METHODS
  This is a HIPAA-compliant, IRB-approved retrospective study. Our institutional database and teaching files were searched for cases of cholangiocarcinomas diagnosed between 2004 and 2014 that were initially misdiagnosed or considered indeterminate lesions on MRI or CT. Clinical data and radiological findings were collected. History of malignancy and risk factors for cholangiocarcinoma were recorded. The initial reported diagnosis and time to the correct diagnosis were noted, and the lesions were evaluated for size, enhancement, T1/T2 signal, diffusion restriction, ADC value, capsular retraction, biliary dilatation and the presence of satellite nodules.
  
  
  RESULTS
  Nine examples of cholangiocarcinoma that met our inclusion criteria were identified: seven men and two women. All were small, with a mean size of 2.2 cm upon initial diagnosis. All showed a hypervascular pattern of enhancement without washout. Imaging features that are described in the literature as typical for cholangiocarcinomas, such as capsular retraction, satellite nodules, and peripheral biliary dilatation, were not seen.
  
  
  CONCLUSIONS
  Cholangiocarcinomas can be misdiagnosed when they are small and hypervascular. This atypical hypervascular appearance is rare, and may mimic benign liver lesions and other malignant lesions, especially when small. Awareness of the confounding imaging features of these tumors should lead to a more meticulous evaluation of small hypervascular lesions, and may minimize the risk of misdiagnosing early-stage cholangiocarcinomas.
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 676 North Saint Clair Street, Suite 800, Chicago, IL, 60611, USA.
authors.forename: Sharon Z
authors.initials: SZ
authors.lastname: Adam
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 676 North Saint Clair Street, Suite 800, Chicago, IL, 60611, USA.
authors.forename: Sudharshan
authors.initials: S
authors.lastname: Parthasarathy
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, 676 North Saint Clair Street, Suite 800, Chicago, IL, 60611, USA. fmiller@northwestern.edu.
authors.forename: Frank H
authors.initials: FH
authors.lastname: Miller
mesh_terms: D000368:Aged; D001650:Bile Duct Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D001652:Bile Ducts / Q000473:pathology; D018281:Cholangiocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D002758:Cholangiography; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
keywords: Cholangiocarcinoma; Computed tomography; Hypervascular; Liver; Magnetic resonance imaging