Natural history of focal nodular hyperplasia of the liver: an ultrasound study.

Sixteen cases of focal nodular hyperplasia (FNH) of the liver were followed by ultrasound (US) for a mean of 33 months (range 6-81). In 69% of the cases, the diagnosis was incidental. On US the lesions were single in 75% of the cases, localized in the right lobe in 75%, and subcapsular in 50%. No specific US-pattern could be identified. A central scar was found in 19% of the patients. At the end of the follow-up, the size was reduced in 7/16 cases, and in 1/16 the lesion disappeared. The spontaneous reduction of nodules in FNH must be considered in the management of this pseudotumor.