title: MRI of atypical focal nodular hyperplasia of the liver: radiology-pathology correlation.
abstract: OBJECTIVE
  The purpose of our study was to determine the MRI features of atypical focal nodular hyperplasia of the liver and to compare them to pathology findings.
  
  
  METHODS
  We retrospectively reviewed MRI and pathology findings in 27 focal nodular hyperplasia lesions with atypical MRI features. Six criteria for typical focal nodular hyperplasia were required: iso- or hypointensity on T1-weighted sequences and iso- or slight hyperintensity on T2-weighted sequences; homogeneous signal intensity; central hyperintense area on T2-weighted sequences; marked lesion contrast enhancement; accumulation of gadolinium chelates within the central area on delayed contrast-enhanced T1-weighted sequences; and absence of capsule.
  
  
  RESULTS
  The most common atypical radiology features included absence of, or an atypical, stellate area; heterogeneity on both T1- and T2-weighted images; and high-intensity signal on T1-weighted sequences. MRI-pathology correlation showed that T1 hyperintensity with no other atypical MRI feature (n = 3) could be explained by steatosis, sinusoidal dilatation, or hemorrhage. In addition, in two patients with lesions smaller than 3 cm in diameter, the only atypical MRI feature was absence of a stellate area.
  
  
  CONCLUSIONS
  These findings suggest a lesion that is hyperintense on T1-weighted sequences or that lacks a stellate area but is smaller than 3 cm in diameter can be diagnosed as focal nodular hyperplasia provided all other MRI criteria for this diagnosis are present. In such cases, close monitoring on MRI without invasive diagnostic procedures may be warranted. However, in large lesions (> 3 cm) without a stellate area and in lesions with heterogeneity, histopathology examination is mandatory to rule out other diagnoses.
authors.affiliation: Département de Pathologie, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris et Université Paris 12-Val de Marne, Créteil 94010, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Ferlicot
authors.forename: Hicham
authors.initials: H
authors.lastname: Kobeiter
authors.forename: Jeanne
authors.initials: J
authors.lastname: Tran Van Nhieu
authors.forename: Daniel
authors.initials: D
authors.lastname: Cherqui
authors.forename: Daniel
authors.initials: D
authors.lastname: Dhumeaux
authors.forename: Didier
authors.initials: D
authors.lastname: Mathieu
authors.forename: Elie Serge
authors.initials: ES
authors.lastname: Zafrani
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D008099:Liver / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies