What is the recommended management for focal nodular hyperplasia (FNH)?

Management of Focal Nodular Hyperplasia (FNH)

Focal nodular hyperplasia (FNH) requires no monitoring or treatment, regardless of size, as it has no malignant potential and does not require intervention. 1

Characteristics and Diagnosis

FNH is the second most common benign liver lesion after hemangioma, with a prevalence of 0.3% to 3%, and is commonly diagnosed in reproductive-aged women 1. Key features include:

• Typical imaging findings:

  • Strong hyperperfusion from a central artery in arterial phase ("spoke-wheel" appearance)
  • Filled with contrast agent after a few seconds ("lightbulb" sign)
  • Mostly hyper- or isoechoic in late phase 1
  • Central stellate scar containing a large artery with radiating vessel branches 1

• Diagnostic modalities:

  • MRI has higher sensitivity and specificity than ultrasound or CT 2
  • Contrast-enhanced ultrasound (CEUS) can demonstrate the characteristic spoke-wheel appearance 1

Management Recommendations

1. Conservative management is the standard approach

   • No monitoring is required for FNH, regardless of size 1
   • No intervention is needed for asymptomatic patients 2

2. Special considerations:

   • Pregnancy: FNH does not require monitoring during pregnancy 1
   • Oral contraceptives: Both contraceptive use and pregnancy are considered safe with FNH 1

3. Indications for surgical intervention (rare):

   • Persistent symptomatic lesions with upper abdominal pain after extensive investigation for other causes 3
   • Unusual behavior such as rapid growth 3
   • Inability to definitively distinguish from hepatocellular adenoma or malignancy 4

Important Distinctions from Other Liver Lesions

• Hepatocellular adenoma (HCA): Unlike FNH, HCAs require monitoring during pregnancy and may need intervention if ≥5 cm due to risk of rupture 1
• Hemangioma: Like FNH, hemangiomas generally don't require monitoring during pregnancy 1
• Malignant lesions: FNH must be distinguished from hepatocellular carcinoma and hypervascular metastases 5

Common Pitfalls to Avoid

1. Misdiagnosis: FNH can be mistaken for hepatocellular adenoma or malignancy, potentially leading to unnecessary interventions 5

2. Unnecessary monitoring: Unlike hepatocellular adenomas, FNH does not require monitoring during pregnancy or with oral contraceptive use 1

3. Unnecessary biopsy or surgery: Asymptomatic FNH with typical imaging features does not require biopsy or surgical removal 2

4. Confusing with FNH-like nodules: In certain conditions like Fontan-associated liver disease, FNH-like nodules may appear and require different management approaches 1

The evidence strongly supports conservative management for FNH, with the 2021 American Association for the Study of Liver Diseases guidance and 2023 European Association for the Study of the Liver guidelines both explicitly stating that FNH requires no monitoring or intervention in most cases.