Focal nodular hyperplasia
- 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.
 Imaging Findings
- 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.
- 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.
- 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.
- Will display uptake on sulfur colloid scan as FNHs contain Kupffer cells.
- Other hepatic lesions will be cold defects on sulfur colloid scans.
 See Also
 External Links
- Shahid M. Hussain, Türkan Terkivatan, Pieter E. Zondervan, Esmée Lanjouw, Sjoerd de Rave, Jan N. M. IJzermans, and Rob A. de Man. Focal Nodular Hyperplasia: Findings at State-of-the-Art MR Imaging, US, CT, and Pathologic Analysis. RadioGraphics 2004 24: 3-17.
- E-medicine radiology article