Focal nodular hyperplasia (FNH)

Focal nodular hyperplasia is a rare tumor like structure classified in the group of benign lesions that is more frequently seen in females. It is mostly asymptomatic. The origin of FNH is not clear, but pathologists suggest that vascular malformation or vascular injury may cause FNH. FNH does not bleed and often includes central scar that looks like a spoked wheel.

MRI appearance of a focal nodular hyperplasia without (pre-contrast) and with Primovist^®

The central scar is characteristic for FNHs, but is not present in all cases (according to the scientific publications, central scar is present in 40-60% of FNHs).

After injection of Primovist^® in the dynamic phases, early arterial enhancement of the periphery of the lesion and delayed enhancement of the central scar (arrow). In the liver-specific phases, FNH (arrow head) shows an uptake of the agent and appears heterogenous and hyperintense (bright areas) to isointense in comparison to the surrounding parenchyma. In the presence of a central fibrous scar, non-enhancing central regions and septa can be demonstrated (right-hand-side).

Precontrast: T2-weighted sequence

After injection, T1-weighted, liver-specific phase

Therapy

The treatment of FNH is controversial. Most experts exclusively recommend surgery when removing large nodules or those that are causing pain. Smaller nodules are most often left alone and followed with periodic imaging tests used to monitor their size.