[Focal nodular hyperplasia and hepatocellular adenoma]

Area of Science:

• Hepatobiliary imaging
• Liver lesion characterization
• Diagnostic radiology

Context:

• Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are common and rare liver lesions, respectively, predominantly affecting middle-aged women.
• Differentiating between atypical FNH and HCA subtypes presents a diagnostic challenge for conventional imaging modalities.
• Accurate distinction is crucial due to FNH's benign nature versus HCA's potential for hemorrhage, growth, and malignant transformation.

Purpose:

• To review the histopathological and radiological features of FNH and HCA.
• To evaluate the advantages and limitations of various imaging modalities for differentiating these liver lesions.
• To highlight the role of modern hepatobiliary contrast-enhanced MRI in improving diagnostic accuracy.

Summary:

• Conventional imaging (US, CT, MRI) can diagnose typical FNH but struggles with atypical cases and HCA differentiation.
• Hepatobiliary contrast-enhanced MRI demonstrates high sensitivity and specificity for differentiating FNH from metastases and most HCA subtypes.
• New HCA classifications based on phenotype, genotype, and imaging features aid in tailored management strategies.

Impact:

• Improved non-invasive differentiation of FNH and HCA, reducing the need for invasive procedures.
• Enhanced diagnostic confidence in managing liver lesions, particularly atypical FNH.
• Facilitates individualized management plans for HCA based on its subtype and associated risks.