Pediatric Focal Nodular Hyperplasia

  • Etiology: Benign vascular tumor composed of functioning hepatocytes
  • Imaging:
    — Enhances to level of inferior vena cava and does not enhance to level of aorta
    — Feeding vessel goes to center of lesion
    — Central scar often vascular on arterial phase but isodense on later phases
    — Lesion becomes isodense in late venous phase
    — No hemorrhage or necrosis
  • Imaging CT:
    — Isodense or hyperdense on non contrast
    — Hypervascular with homogenous enhancement with large feeding artery on arterial phase
    — Isodense to liver on venous phase
  • Imaging MRI:
    — T1WI:
    — T1WI post contrast: Classically completely fills in with gadoxetate disodium, central scar is myxoid and has delayed enhancement
    — T2WI: Central scar is myxoid making it hyperintense
  • DDX: Hepatic adenoma, hepatic hemangioma
  • Complications:
  • Treatment: Rarely surgically resected
  • Clinical:
    — Normal AFP
    — Less than 20% of patients are symptomatic
    — Female preponderance
    — Seen in three populations: solitary lesion in 2-5 years old and adolescents and multiple lesions as late complication post chemotherapy (regenerating hepatic nodules)

Radiology Cases of Focal Nodular Hyperplasia

Axial and coronal CT with contrast of the abdomen arterial phase imaging (left) shows an enhancing round lesion in the dome of the liver that has a central scar which fills in on the portal venous phase imaging and becomes isodense with the surrounding liver parenchyma (center). Axial T1 MRI with Eovist (hepatocyte specific) contrast of the abdomen in the arterial phase (right upper) again shows the enhancing round lesion with a central scar that fills in the portal venous phase imaging (right center) and then retains its contrast on the delayed phase imaging (right lower).
US and MRI of focal nodular hyperplasia
Transverse US of the liver (above left) shows a round hyperechoic lesion in the liver. Coronal T2 MRI without contrast of the abdomen (above right) shows the lesion in the right lobe of the liver to have slightly increased signal intensity aside from the center of the lesion which has high signal intensity. Axial T1 MRI with contrast of the abdomen obtained in early phase imaging (below left) shows near uniform enhancement of the lesion aside from the center of the lesion while delayed phase imaging (below right) shows delayed stellate-like enhancement of the center of the lesion while the rest of the lesion is now isointense to liver.