What is the best course of action for a 1.2 cm hyperenhancing nodule in the posterior dome of the liver, with differential diagnoses of hemangioma (benign vascular tumor) or focal nodular hyperplasia (FNH)?

Management of 1.2 cm Hyperenhancing Liver Nodule: Hemangioma vs FNH

For a 1.2 cm hyperenhancing nodule in the posterior dome of the liver with differential diagnoses of hemangioma versus focal nodular hyperplasia, proceed directly to MRI with gadolinium contrast as the definitive diagnostic test, which has 95-99% accuracy for distinguishing these benign lesions and will guide conservative management without need for biopsy. 1

Diagnostic Algorithm

First-Line Advanced Imaging: MRI with Contrast

• MRI with gadolinium is the gold standard for characterizing this lesion, achieving 95-99% accuracy for hemangioma diagnosis and 88-99% accuracy for FNH diagnosis 1
• MRI establishes a definitive diagnosis in 95% of liver lesions, significantly outperforming CT (which requires further imaging in 10% of cases versus only 1.5% with MRI) 1
• The combination of diffusion-weighted imaging (DWI) and hepatobiliary phase (HBP) imaging correctly classifies lesions as benign or malignant in 91% of cases and provides exact characterization in 85% of cases 1

Alternative: Contrast-Enhanced Ultrasound (CEUS)

If MRI is contraindicated or unavailable, CEUS is highly effective:

• For hemangioma detection: CEUS shows peripheral nodular enhancement (74% of cases) in the arterial phase with complete (78%) or incomplete (22%) centripetal filling in portal venous and late phases 1, 2
• For FNH detection: CEUS demonstrates strong hyperperfusion from a large, tortuous feeding artery creating a characteristic spoke-wheel appearance, with the lesion appearing more enhanced than surrounding liver (the "lightbulb" sign) 1, 3
• CEUS has 100% sensitivity and 87% specificity for identifying FNH and hemangiomas, with overall accuracy of 94.5% 4

Distinguishing Features on Imaging

Hemangioma Characteristics

• Typical appearance: Peripheral nodular enhancement with gradual centripetal filling 1, 2
• Small hemangiomas (<2 cm) usually appear uniformly echogenic on ultrasound 2
• On MRI: hyperintense on T2-weighted images with characteristic discontinuous peripheral nodular enhancement and progressive centripetal fill-in 5
• High-flow hemangiomas may show rapid enhancement but maintain the peripheral nodular pattern (slow-motion review may be needed) 1

FNH Characteristics

• Pathognomonic finding: Spoke-wheel vascular pattern from central feeding artery radiating outward 1, 3
• Typically hyperechogenic on B-mode ultrasound 1
• On MRI: iso- or hypointense on T1, slightly hyper- or isointense on T2, with hyperintense central scar on T2-weighted images 5
• Intense homogeneous enhancement during arterial phase with enhancement of central scar in later phases 5
• On gadoxetate-enhanced MRI, FNH typically shows iso- or hyperintensity in hepatobiliary phase (unlike adenoma which is hypointense) 1

Management Based on Diagnosis

If Hemangioma is Confirmed

• No intervention or routine surveillance required for typical-appearing hemangiomas in patients at low risk for malignancy 2
• Conservative observation is appropriate as hemangiomas rarely require intervention unless giant (>5 cm), symptomatic, or showing rapid growth 2
• Biopsy is contraindicated due to bleeding risk 2

If FNH is Confirmed

• No intervention required as FNH has extremely low risk of spontaneous rupture (only one case reported in literature) 3
• No routine surveillance imaging needed 3
• Pregnancy is not contraindicated and vaginal delivery carries no increased risk 3
• Unlike hepatic adenomas, FNH does not require monitoring during pregnancy or pre-pregnancy intervention regardless of size 3

Critical Pitfalls to Avoid

Biopsy Considerations

• Avoid biopsy for suspected hemangiomas due to significant bleeding risk 1, 2
• Biopsy is only indicated when imaging remains inconclusive after MRI and malignancy cannot be excluded 1, 2
• If biopsy is necessary, CEUS guidance increases technical success rate from 74% to 100% 1

Diagnostic Confusion

• High-flow hemangiomas can mimic HCC or FNH if the nodular pattern and centripetal flow are not recognized 1
• FNH can show washout in late phase (especially in patients >35 years), potentially mimicking malignancy 1
• FNH may coexist with hemangiomas in up to 20% of cases 3, 6
• Inflammatory adenomas can mimic FNH on MRI, though this is less relevant at 1.2 cm size 1

Size-Specific Considerations

• At 1.2 cm, this lesion falls into the category where dynamic contrast-enhanced imaging (CT/MRI) is recommended for evaluation 1
• Both hemangioma and FNH at this size are managed conservatively once diagnosis is established 2, 3
• CT without contrast adds no value and should not be performed 1