What is the recommended follow-up for patients with focal nodular hyperplasia (FNH) of the liver?

Management and Follow-up of Focal Nodular Hyperplasia (FNH) of the Liver

Focal nodular hyperplasia (FNH) of the liver typically requires no specific follow-up or treatment as it is a benign condition with no malignant potential and rarely causes symptoms. Conservative management is appropriate for the vast majority of cases.

Diagnostic Characteristics of FNH

• FNH is the second most common benign solid liver tumor after hemangioma, occurring more frequently in young women 1
• Typical imaging features include:
  • Strong hyperperfusion from a central artery in the arterial phase creating a "spoke-wheel" appearance on contrast-enhanced ultrasound (CEUS) 2
  • Centrifugal filling pattern that may be rapid 2
  • "Light bulb" sign (lesion more enhanced than surrounding liver) 2
  • Hyper- or isoechoic appearance in the late phase 2

Follow-up Recommendations

• For typical, asymptomatic FNH with characteristic imaging features:

  • No specific follow-up is required as these lesions have no malignant potential 3
  • Conservative management is effective in approximately 94.4% of cases 3

• For atypical FNH or when diagnosis is uncertain:

  • First follow-up imaging at 6 months, and if stable for 12 months, return to normal surveillance interval 4
  • If the nodule grows or changes its enhancement pattern during follow-up, further investigation should be considered 4

• For FNH lesions <1 cm:

  • Follow-up ultrasound at 3-4 month intervals in the first year 5
  • If stable for 12 months, return to regular six-month surveillance 4

Indications for Intervention

Intervention is rarely required for FNH and should be considered only in specific circumstances:

• Persistent, significant symptoms clearly attributable to the FNH lesion after excluding other causes 6
• Rapid or significant growth during follow-up 6
• Uncertainty in diagnosis despite appropriate imaging and/or biopsy 4

Special Considerations

• FNH/FNH-like lesions can occur in cancer survivors and may mimic relapsed malignancy; recognizing these benign lesions can help avoid unnecessary invasive procedures 7
• FNH should be managed similarly to hemangiomas, with observation being appropriate for most lesions 6
• For complex or atypical cases, multidisciplinary team discussion is recommended 4

Pitfalls to Avoid

• Misdiagnosing FNH as hepatocellular adenoma, hepatocellular carcinoma, or hypervascular metastasis, which could lead to unnecessary interventions 1
• Performing surgery for typical, asymptomatic FNH lesions, as surgical intervention is almost never required 3
• Failing to recognize that washout phenomenon can sometimes be observed in the late phase due to bubble destruction or degenerative changes, especially in patients older than 35 years, which might lead to confusion with malignant lesions 2