High serum level of alpha-fetoprotein in focal nodular hyperplasia of the liver.

Serum alpha-fetoprotein (AFP), the main serum marker of hepatocellular carcinoma, may increase in some benign conditions involving the liver but is usually within normal values in focal nodular hyperplasia (FNH) in adults. We present a case of a FNH associated with serum AFP increase, and in which both the lesion and the non-lesional adjacent liver showed AFP-positive immunostained areas. Moreover, only one case of FNH with AFP-positive immunostaining has been previously reported. In addition, our case of FNH is remarkable as it displayed some morphological and immunophenotypical features of progenitor cells. The serum AFP levels rose after liver resection and progressively returned to the preoperative high values. These findings are concordant with the hypothesis that FNH is a regenerative process, and suggest that regenerative areas in the liver might be the source of AFP production.