title: [Focal nodular hyperplasia and hepatocellular adenoma].
abstract: OBJECTIVE
  Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are liver lesions of hepatocellular origin. The FNH is a commonly occurring hepatic lesion whereas HCA is very rare. Non-invasive differentiation between HCA subtypes and atypical FNH may pose a diagnostic challenge as both entities predominantly occur in middle-aged female patients.
  
  
  METHODS
  The conventional imaging modalities include ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Distinguishing FNH from HCA is of great importance clinically as FNH is considered to be a benign lesion and needs no further management. In contrast HCA is considered to be a borderline tumor due to the risk of hemorrhage, growth and even malignant transformation and requires individualized management.
  The above mentioned radiological procedures usually enable an accurate and certain diagnosis of a typical FNH to be achieved. In cases of atypical FNH, particularly in patients with a clinical history of malignancy, these imaging modalities are insufficient to establish a clear diagnosis. In this scenario, the use of modern hepatobiliary contrast-enhanced MRI will enable a differentiation between FNH and metastasis with a high sensitivity and specificity. Furthermore, it allows a differentiation of FNH from 90 % of adenoma subtypes.
  
  
  RESULTS
  This article describes the histopathological and radiological features of these lesions and explains the advantages and limitations of various imaging modalities used for the diagnosis and differentiation of these entities.
  
  
  CONCLUSIONS
  The new classification of HCAs according to phenotype and genotype and their imaging features, as well as different enhancement patterns, are described. The correlation between HCA subtypes and their individual management are also discussed.
authors.affiliation: Universitätsklinik für Radiologie und Nuklearmedizin, Abteilung für Allgemeine Radiologie und Kinderradiologie, Department of Biomedical Imaging and Image-guided Therapy, Medizinische Universität Wien, Währinger Gürtel 18-20, 1090, Wien, Österreich, nina.bastati@meduniwien.ac.at.
authors.forename: N
authors.initials: N
authors.lastname: Bastati-Huber
authors.forename: S
authors.initials: S
authors.lastname: Pötter-Lang
authors.forename: A
authors.initials: A
authors.lastname: Ba-Ssalamah
mesh_terms: D018248:Adenoma, Liver Cell / Q000175:diagnosis*; D003937:Diagnosis, Differential; D020518:Focal Nodular Hyperplasia / Q000175:diagnosis*; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*