Background and Purpose: The serum alpha-fetoprotein (AFP) level has been used as a tumor marker for hepatoblastoma, and malignant germ cell tumors in pediatric patients. The AFP has 3 isoforms (L1, L2, L3), and the usefulness of the L3 fraction as a diagnostic marker for the adult hepatocellular carcinoma is well known. However, there are few reports dealing with various pediatric malignant tumors. In the current study, we analyzed the diagnostic value of AFP fractions for pediatric diseases, in particular, those occurring in the neoinfantile period.
Materials and Methods: From 2003 to 2006, two cases of hepatoblastoma, and 5 cases of germ cell tumor, all of which were neoinfantile, were treated in our department. In our analytical system (LiBASys), the level of the L3 fraction contains the majority of the L2 fraction. The total AFP (ng/mL) level and the L3 fraction (%) were measured to assess the usefulness of the L3 fraction as a diagnostic marker.
Results: In all cases of hepatoblastoma and yolk sac tumor, both the total AFP and the L3 fraction were high, either before treatment or in the presence of malignant tumors. Most of the cases of neonatal immature teratoma showed a high total AFP level during the neoinfantile period, however, the L3 fraction was around 10%, and decreased after surgical treatment. Only 1 case of the immature teratoma demonstrated malignant transformation, when the patient was 8 months old. As the total AFP and the AFP-L3 fraction were proportionally elevated, the patient was treated with additional surgical resection and chemotherapy. In the case of neonatal mature teratoma, the L3 fraction was below 0.5%, even when the total AFP level was high.
Discussion: Our results indicated that the level of the L3 fraction accurately confirmed the existence, or the malignant potential of hepatic tumor or germ cell tumor. The L3 fraction is useful as a tumor marker during the neoinfantile period.