IMMUNOHISTOCHEMICAL EVALUATION OF HEPATOBLASTOMAS WITH USE OF THE HEPATOCYTE-SPECIFIC MARKER, HEPATOCYTE-PARAFFIN-1, AND THE POLYCLONAL ANTICARCINOEMBRYONIC ANTIGEN

The distinction of hepatoblastoma, especially the embryonal type, from other small, round-cell tumors of childhood can sometimes be difficul t, Polyclonal anticarcinoembryonic antigen (pCEA) and Hepatocyte Paraf fin 1 (Hep Par 1) are immunohistochemical markers that are useful in t he diagnosis of hepatocellular carcinomas. We immunohistochemically st udied pCEA, monoclonal CEA (mCEA), and Hep Par 1 on 12 hepatoblastomas (3 fetal type, 2 embryonal type, and 7 mixed epithelial type). In add ition, we studied the expression of Hep Par 1 on 27 other selected chi ldhood tumors, including 1 hepatocellular carcinoma, 5 germ-cell tumor s, 4 peripheral neuroectodermal tumors / Ewing's sarcomas, 3 rhabdomyo sarcomas, 5 neuroblastomas, 2 rhabdoid tumors, 3 lymphomas, and 4 Wilm s' tumors. All of the hepatoblastomas expressed Hep Par 1 with a chara cteristic granular intracytoplasmic pattern that was generally less in tense in embryonal-type than in fetal-type hepatoblastomas, perhaps re flecting the degree of hepatocyte differentiation. All of the fetal-ty pe hepatoblastomas expressed pCEA with both an intracytoplasmic and bi le canalicular pattern. Embryonal type hepatoblastomas were more likel y to be pCEA negative or to show focal or no canalicular pattern of ex pression, again possibly reflecting the degree of hepatocyte different iation. All of the hepatoblastomas were mCEA negative. All of the nonh epatoblastomas were Hep Par 1 negative, except for the one hepatocellu lar carcinoma in this study, which was Hep Par 1 positive. We conclude that Hep Par 1 and pCEA are useful markers for hepatoblastomas, as th ey have been shown to be in hepatocellular carcinomas.