Focal nodular hyperplasia

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[edit] Discussion

  • Focal nodular hyperplasia (FNH) is the second most common tumor of the liver (hepatic hemangioma is the most common).
  • FNH is believed to occur as a result of a localized hepatocyte response to an underlying congenital arteriovenous malformation.
  • FNH is a hyperplastic process in which all the normal constituents of the liver are present but in an abnormally organized pattern.
  • Malignant transformation of FNH has not been reported.
  • FNH must be differentiated from fibrolamellar carcinoma, with which it shares imaging and gross features.
  • Male-to-female ratio is 1:2-4.

[edit] Imaging Findings

[edit] CT

  • Lobulated contours at CT.
  • At unenhanced CT, the lesions are either hypoattenuating or isoattenuating to the surrounding liver.
  • In the arterial phase, the lesions become hyperattenuating due to the homogeneous intense enhancement of the entire lesion, except the central scar.
  • In the portal and later phases, the lesions become more isoattenuating with the surrounding liver and the central scar may show some enhancement.

[edit] MRI

  • Often isointense on T1-weighted images.
  • Often isointense on T2-weighted images.
  • Central scar
    • Hypointense on T1-weighted images
    • Variable signal-intensity pattern on T2-weighted images.
  • Contrast
    • Dense enhancement is seen in the arterial phase,
    • Isointense during the portal venous phase
    • Isointense on delayed images.
    • Late and prolonged enhancement of the central stellate scar occasionally occurs.

[edit] Nucs

  • Will display uptake on sulfur colloid scan as FNHs contain Kupffer cells.
  • Other hepatic lesions will be cold defects on sulfur colloid scans.

[edit] Images

Patient #1

[edit] See Also

[edit] External Links

[edit] References