KEY FACTS
Terminology
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Focal nodular hyperplasia (FNH)
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Benign tumor of liver caused by hyperplastic response to localized vascular abnormality
Imaging
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US
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Usually homogeneous and isoechoic
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Spoke-wheel pattern on color Doppler US
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Large central feeding artery with multiple small vessels radiating peripherally
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CEUS/CT/MR
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Bright, homogeneously enhancing mass in centrifugal direction on arterial phase (CEUS) with delayed enhancement of central scar (CT/MR)
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Gadoxetate-enhanced MR
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Most specific test to diagnose FNH
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Prolonged enhancement of entire FNH on hepatobiliary phase scan
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Top Differential Diagnoses
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Hepatic adenoma
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Fibrolamellar hepatocellular carcinoma
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Hepatic cavernous hemangioma
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Hypervascular metastasis
Pathology
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Normal hepatocytes and malformed bile ductules
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Thick-walled arteries in fibrous septa radiating from center to periphery
Clinical Issues
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Common in young to middle-aged women
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Excellent prognosis
Diagnostic Checklist
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Imaging is more reliable than histology in making diagnosis of FNH
Scanning Tips
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Look for radiating vessels that flow in centrifugal direction (away from center) with color Doppler
with a central scar and thin, radiating septa dividing the mass into hyperplastic nodules. Note the cluster of small arteries near the central scar.
, typical of focal nodular hyperplasia. (Courtesy M. Yeh, MD, PhD.)
. The mass causes contour deformity and mass effect upon the adjacent gallbladder and portal vein 
. The lesion is difficult to distinguish from the surrounding liver, earning its moniker “stealth lesion.”Related posts:
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