Diagnosis of focal nodular hyperplasia. Role of imaging techniques

Focal nodular hyperplasia (FNH) is a rare benign liver lesion which is difficult to differentiate from other benign liver pathologies and hepatocellular carcinoma. However, with appropriate new imaging techniques it is, at present, possible to diagnose this lesion with certainty thus avoiding invasive tests. Patient follow-up is also facilitated. It is often incidentally discovered during an abdominal ultrasound for other pathologies. Color power Doppler allows, in most cases, one to distinguish it from other focal liver lesions. However, in doubtful cases contrast-enhanced computed tomography and magnetic resonance imaging can help us to define the exact nature of the lesion. It is only occasionally necessary to perform an ultrasound-guided liver biopsy of the nodule and anyhow, once a correct diagnosis has been made, in most cases there is no indication for surgery. In spite of the contradictory results in the literature on the effects of oral contraceptives and pregnancy on the evolution of FNH, it now seems that they do not condition the appearance or the size of FNH and that in a woman with FNH pregnancy should not only be discouraged, but rather favored and closely monitored.