Focal nodular hyperplasia (FNH) is a benign tissue reaction to an area of denser liver cell growth in response to increased blood/nutrient supply from a larger than usual artery in that area. The dense liver cell growth appears as a mass on imaging tests.
It is the second most common benign hepatic tumor after hemangioma. Other names for this entity include solitary hyperplastic nodule, hepatic hamartoma, focal cirrhosis, and hepatic pseudotumor. FNH is generally asymptomatic, discovered with imaging tests. Diagnosis can be made with CT or MRI imaging, but sometimes biopsy is needed. FNH occurs predominantly more in women than men (8 or 9:1 ratio) and is seen in patients between the ages of 20-50.
It is not necessary to stop oral contraceptive pills or estrogen therapy since these lesions are not hormone sensitive. Care for these tumors are dependent on size and symptoms of the FNH. Given that FNH are often asymptomatic and small, the treatment is usually conservative.