Ring-like enhancement of focal nodular hyperplasia with hepatobiliary-phase Gd-EOB-DTPA-enhanced magnetic resonance imaging: radiological-pathological correlation.

We report a case of focal nodular hyperplasia in a patient for whom gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and histological analysis results were available. Dynamic contrast-enhanced computed tomography showed a well-defined hypervascular lesion 14 mm in diameter with no visible central scars. Gd-EOB-DTPA-enhanced MRI demonstrated strong peripheral enhancement of the lesion during the hepatobiliary phase, resulting in ring-like enhancement. The pathology examination revealed that the lesion was focal nodular hyperplasia (FNH). Immunohistochemistry showed positive expression of OATP8 in the hepatocytes in the peripheral areas of the lesion, whereas expression of OATP8 was lacking in hepatocytes surrounding the central radiating scar. Ring-like enhancement during the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI may be an important clue for the diagnosis of small FNH.