title: Inflammatory hepatocellular adenomas can mimic focal nodular hyperplasia on gadoxetic acid-enhanced MRI.
abstract: OBJECTIVE
  Inflammatory hepatocellular adenoma (HCA) is a recently categorized entity of hepatocellular neoplasms. We investigated whether gadoxetic acid-enhanced MRI can distinguish inflammatory HCA from focal nodular hyperplasia (FNH).
  
  
  METHODS
  From January 1, 2009, through January 1, 2013, gadoxetic acid-enhanced MRI examinations from two institutions were reviewed for HCA, with specific histologic features of inflammatory HCA. Biopsy and resection slides were reviewed, and immunohistochemistry for glutamine synthetase was performed in a subset to confirm the initial diagnosis.
  
  
  RESULTS
  A total of 10 possible cases of inflammatory HCA were identified in the pathology database. On the basis of glutamine synthetase staining performed for this study, three cases were rediagnosed as FNH and thus were excluded from the study. Therefore, a total of seven patients with inflammatory HCA were identified. On gadoxetic acid-enhanced MRI, four of these patients had classic features of FNH (group A, FNH mimics), and three had imaging features suggestive of HCA (group B, typical inflammatory HCA). Imaging features that were considered diagnostic of FNH included isointense or minimal T2 hyperintensity, arterial enhancement, and diffuse hyperintensity on hepatobiliary phase. Three of the four patients with FNH mimics had slides available for pathologic rereview, and the diagnosis of inflammatory HCA was supported by glutamine synthetase immunohistochemistry findings. The pathology reports of the remaining four cases were rereviewed and were also found to have features consistent with inflammatory HCA.
  
  
  CONCLUSIONS
  Inflammatory HCA can mimic FNH on MRI, including hepatobiliary phase hyperintensity. Moreover, conventional pathology using histopathology alone may lead to misclassification of inflammatory HCA.
authors: 1 Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Boston, MA 02114.
authors: Sheela
authors: S
authors: Agarwal
authors: Jorge M
authors: JM
authors: Fuentes-Orrego
authors: Thomas
authors: T
authors: Arnason
authors: Joseph
authors: J
authors: Misdraji
authors: Kartik S
authors: KS
authors: Jhaveri
authors: Mukesh
authors: M
authors: Harisinghani
authors: Peter F
authors: PF
authors: Hahn
mesh_terms: D018248:Adenoma, Liver Cell / Q000150:complications / Q000473:pathology*; D000328:Adult; D003287:Contrast Media; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D020518:Focal Nodular Hyperplasia / Q000473:pathology*; D019786:Gadolinium DTPA; D006505:Hepatitis / Q000150:complications / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008113:Liver Neoplasms / Q000150:complications / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: contrast-enhanced MRI; gadoxetate disodium; inflammatory hepatocellular adenoma; liver imaging