title: Radiological features of focal nodular hyperplasia of the liver in children.
abstract: BACKGROUND
  Focal nodular hyperplasia (FNH) is an unusual hepatic tumour in children and should be distinguished from other hepatic lesions.
  
  
  OBJECTIVE
  To describe the imaging characteristics of FNH in children.
  
  
  METHODS
  We examined five patients (three boys and two girls, mean age 9.4 years) with pathologically confirmed FNH. The diagnosis was obtained by tumour resection (n = 4) and percutaneous needle biopsy (n = 1). One patient with multiple FNHs showed recurrent lesions after tumour resection. All patients were studied with US (including colour and power Doppler US [n = 3]) and CT. Dynamic enhanced CT scans were available in three patients. MRI (n = 2) or coeliac angiography (n = 1) was performed in three patients.
  
  
  RESULTS
  Seven of eight FNH lesions in five patients were demonstrated by imaging. The average size of the lesions was 6.5 cm. Six lesions detected on US showed variable echogenicity with a central hyperechoic scar (n = 2). On Doppler examination, central or peripheral hypervascular areas were seen (n = 3). Six lesions detected on contrast-enhanced CT showed high attenuation (n = 4) or iso-attenuation (n = 2). On early phase scans, all the lesions (n = 3) showed high attenuation. Irregular linear or ovoid central scars were detected in two patients on CT. MR demonstrated three lesions in two patients, one of which had not been detected by US or CT. A central low signal intensity scar (n = 1) was seen on T2-weighted MRI. Coeliac angiography performed in one patient showed a hypervascular mass with homogeneous staining.
  
  
  CONCLUSIONS
  FNH in children shows a wide spectrum of imaging findings on various radiological examinations and the typical central scar was not always seen on imaging studies. Dynamic enhanced CT obtained in the early phase and colour Doppler studies may be helpful in the diagnosis of FNH by allowing characterisation of tumour vascularity. FNH should be included in the differential diagnosis of liver mass in children.
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, College of Medicine, Seoul National University, Seoul, Korea.
authors.forename: J E
authors.initials: JE
authors.lastname: Cheon
authors.forename: W S
authors.initials: WS
authors.lastname: Kim
authors.forename: I O
authors.initials: IO
authors.lastname: Kim
authors.forename: J J
authors.initials: JJ
authors.lastname: Jang
authors.forename: J K
authors.initials: JK
authors.lastname: Seo
authors.forename: K M
authors.initials: KM
authors.lastname: Yeon
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000000981:diagnostic imaging / Q000473:pathology; D008099:Liver / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D012008:Recurrence; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography