Focal nodular hyperplasia of the liver: radiologic findings.

A retrospective analysis of the results of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) of 24 cases (28 lesions) of proven focal nodular hyperplasia (FNH) is presented. While US exhibited nonspecific features, CT frequently showed characteristic features: hypodensity on precontrast scans (69%), transient immediate enhancement after bolus injection (96%), and homogeneity (85%). A scar was noted in 31% of the cases. The typical MR triad of isointensity on T1- and/or T2-weighted (T2-WI), homogeneity, and a scar which shows hyperintensity on T2-WI was seen in only 12% of our cases. The most common finding was homogeneity (94%). In two cases the scar was hypointense on T2-WI. To our knowledge, this finding has not been described before. We conclude that the features of FNH, although fairly constant, are at times indistinguishable from those of other hepatic tumors, such as hepatic adenoma (HA), fibrolamellar hepatocellular carcinoma (FLHCC), small hepatocellular carcinoma, and a hyperplastic nodule. Therefore, a multimodality approach is essential for the correct diagnosis in order to prevent unnecessary surgery.