Focal nodular hyperplasia

Focal nodular hyperplasia (FNH) is the second most common benign liver lesion, with an estimated prevalence of up to 3%. It is thought to represent a proliferative cell response to an aberrant dystrophic artery. Ninety percent of cases occur in females, commonly presenting between the ages of 35 and 50 years. In most cases focal nodular hyperplasia is small (less than 5 cm) and solitary, but may be multiple in 20 to 30% of cases.

Typical radiological findings on contrast-enhanced imaging (computed tomography [CT], magnetic resonance imaging [MRI]) include strong, homogeneous enhancement on arterial phase, with iso-intensity to the liver on portal and delayed phases, and the presence of a central scar. MRI has the highest diagnostic performance, with nearly 100% specificity.

For a lesion typical of focal nodular hyperplasia, follow-up imaging is not required and treatment is not indicated.

It is not necessary to discontinue combined oral contraceptives in patients with focal nodular hyperplasia, and follow-up during pregnancy is not required.