[Hepatoblastoma cells producing alpha-fetoprotein: morphometric, immunohistochemical and electron microscopic...

Morphometric, immunohistochemical, and electron-microscopic studies were undertaken in an attempt to identify the types of hepatoblastoma cellular elements responsible for the synthesis of alpha-fetoprotein (AFP), and to see how they may relate to serum AFP levels and the metastatic spread and prognosis of the hepatoblastoma. Morphometric studies of 21 hepatoblastomas with statistical treatment of the results revealed a moderately strong reliable correlation of the AFP serum titer with the volume ratio of embryonal tumor cells and with that of those tumor elements of endodermal hepatic diverticulum which are similar to the latter cells with regard to degree of differentiation. Also, a consistent, reliable negative correlation was demonstrated between serum AFP titer and the volume of fetal hepatoblastoma cells. The volume ratio of stromal elements was found to be subject to chance variations and not to correlate with serum AFP level. Immunohistochemical and electron-microscopic studies confirmed the morphometric findings and showed AFP synthesis to be effected by poorly differentiated hepatoblastoma cells--by endodermal hepatic diverticulum elements at first and by embryonal and intermediate tumor cells later--and to decrease as the liver tumor cells differentiate further. It is concluded that a high serum AFP level is, generally, an indication that the hepatoblastoma is an extensive one and consists of poorly differentiated cells so that the prognosis is unfavorable.