Focal Nodular Hyperplasia

 Hypodense or isodense to normal liver

• Delayed scans
image Mass: Isodense to normal liver

image Central scar: Hyperdense or hyperintense (due to fibrous tissue)

• Gadoxetate-enhanced MR
image Most specific test to diagnose FNH

image Prolonged enhancement of entire FNH (except scar) on delayed scan


• Hepatic adenoma
image Rarely retains gadoxetate on delayed phase MR

• Fibrolamellar hepatocellular carcinoma
image Usually large (> 12 cm) heterogeneous mass

image Has “aggressive” features such as metastases

• Hepatic cavernous hemangioma
image Enhanced portions isodense to vessels

• Hypervascular metastasis
image Usually multiple with known primary tumor


• Imaging is more reliable than histology in establishing diagnosis of FNH

• Diagnosis can be made by CT alone in most cases
image MR with gadoxetate enhancement is most specific test

(Left) Graphic shows a homogeneous, vascular, nonencapsulated mass image with a central scar and thin radiating septa dividing the mass into hyperplastic nodules. Note the cluster of small arteries near the central scar.

(Right) Axial arterial phase CECT shows bright, homogeneous enhancement of a mass image with a central scar image in an asymptomatic young woman who had a mass found on ultrasound. The CT findings in this case are diagnostic of FNH and require no further evaluation.

(Left) This liver wedge resection shows a well-circumscribed nodular lesion with a central stellate scar image, typical of FNH. (Courtesy M. Yeh, MD, PhD.)

(Right) The central scar as well as the fibrous septa may contain thick-walled vessels image. (Courtesy M. Yeh, MD, PhD.)



• Focal nodular hyperplasia (FNH)


• Benign tumor of liver caused by hyperplastic response to localized vascular abnormality


General Features

• Best diagnostic clue
image Bright, homogeneously enhancing mass on arterial phase CT or MR with delayed enhancement of central scar
– Hyperintense enhancement on hepatobiliary phase of gadoxetate-enhanced MR

• Location
image Usually subcapsular and rarely pedunculated

• Size
image Majority are < 5 cm unless symptomatic

• Morphology
image Spherical nonencapsulated mass

• Key concepts
image 2nd most common benign tumor of liver

image Benign congenital hamartomatous malformation

image Accounts for 8% of primary hepatic tumors in autopsy series

image Usually solitary lesion (80%); multiple (20%)

image Multiple FNHs are associated with multiorgan vascular malformations and certain brain neoplasms

CT Findings

image Isodense or hypodense to normal liver

image Hepatic arterial phase scan
– Transient, intense, homogeneous hyperdensity

image Portal venous phase scan
– Hypodense or isodense to normal liver

– Large draining veins → hepatic veins

image Delayed scans
– Mass: ∼ isodense to normal liver

– Central scar: Hyperdense (due to fibrous tissue)

– Scar visible in 2/3 of large and 1/3 of small FNHs
image “Large” > 3 cm

MR Findings

• T1WI
image Mass: Isointense to slightly hypointense

image Central scar: Hypointense

• T2WI
image Mass: Slightly hyperintense to isointense

image Central scar: Hyperintense

• T1WI C+
image Arterial phase: Hyperintense (homogeneous)

image Portal venous: Isointense to liver

image Delayed phase
– Mass: Isointense

– Scar: Hyperintense

• Specific hepatobiliary MR contrast agents
image Gadoxetate (Eovist or Primovist)
– Bright, homogeneous enhancement of FNH on arterial phase

– Prolonged enhancement of entire FNH on hepatobiliary phase (delayed, ∼ 20 minutes)
image Intensity of FNH > liver

image Most specific test to distinguish from all other hepatic masses

image Due to functioning hepatocytes, malformed bile ductules

Ultrasonographic Findings

• Grayscale ultrasound
image Mass: Mostly homogeneous and isoechoic to liver
– Occasionally hypoechoic or hyperechoic

image Central scar: Hypoechoic

• Color Doppler
image Spoke-wheel pattern
– Large central feeding artery with multiple small vessels radiating peripherally

image Large draining veins at tumor margins

image High-velocity Doppler signals
– Due to increased blood flow or arteriovenous shunts

Angiographic Findings

• Conventional
image Arterial phase
– Tumor: Hypervascular

– Scar: Hypovascular

– Enlargement of main feeding artery with centrifugal blood supply

– Same spoke-wheel pattern as on color Doppler

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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Focal Nodular Hyperplasia

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