Diagnostic Ultrasound - Abdomen and Pelvis

Focal Nodular Hyperplasia
Diagnoses: Liver
TERMINOLOGY
• Focal nodular hyperplasia (FNH)
• Benign tumor of liver caused by hyperplastic response to
localized vascular abnormality
IMAGING
• Ultrasound
○ Usually homogeneous and isoechoic
○ Spoke-wheel pattern on color Doppler US
– Large central feeding artery with multiple small
vessels radiating peripherally
• CEUS/CT/MR
○ Bright, homogeneously enhancing mass on arterial
phase with delayed enhancement of central scar
• Gadoxetate-enhanced MR
○ Most specific test to diagnose FNH
○ Prolonged enhancement of entire FNH on hepatobiliary
phase scan
KEY FACTS
TOP DIFFERENTIAL DIAGNOSES
• Hepatic adenoma
• Fibrolamellar hepatocellular carcinoma
• Hepatic cavernous hemangioma
• Hypervascular metastasis
PATHOLOGY
• Normal hepatocytes and malformed bile ductules
• Thick-walled arteries in fibrous septa radiating from center
to periphery
CLINICAL ISSUES
• Common in young to middle-aged women
• Excellent prognosis
DIAGNOSTIC CHECKLIST
• Imaging is more reliable than histology in making diagnosis
of FNH
(Left) Transverse abdominal
US shows a large FNH ſt that
appears as a homogeneously
hypoechoic solid mass in the
lateral segment of the left
lobe of the liver. (Right) On
power Doppler US in the same
patient, the FNH shows a large
central feeding artery with
multiple small vessels
radiating peripherally ſt,
creating a "spoke wheel"
vascularity pattern.
(Left) Axial arterial phase T1
contrast-enhanced MR in the
same patient shows a slightly
hyperenhancing FNH ſt
compared to adjacent liver
parenchyma . The FNH
contains a hypointense
stellate central scar st.
(Right) Delayed phase T1
contrast-enhanced MR in the
same patient shows that the
FNH becomes isointense ſt
compared to background liver
parenchyma. The central scar
is hypointense st but
enhances slightly compared to
the arterial phase image.
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