Hepatoblastoma: an analysis of the relationship between morphologic subtypes and prognosis.

Hepatoblastoma is universally recognized and appreciated as one of the unique embryonic tumors of childhood whose morphologic features attempt to recapitulate some of the developmental aspects of the liver. One of the earliest reports referred to this tumor as a teratoma, and it was not until 60 years later that the hepatoblastoma was clearly differentiated from the hepatocellular carcinoma. With the success of the National Wilms' Tumor Study in the recognition and definition of prognostically favorable and unfavorable pathologic types of Wilms' tumor, efforts have been made in this same direction with hepatoblastoma and other malignancies in the pediatric-age population. This review analyzes the progress that has been made in the delineation of morphologic subtypes of hepatoblastoma and their reliability as indicators of prognosis. We conclude that the data are somewhat contradictory about the significance of pure fetal histology as a favorable factor. There are presently too few observations on the so-called macrotrabecular hepatoblastoma to be certain whether it is prognostically unfavorable or not, but general agreement exists about the poor prognosis associated with the rare small cell or anaplastic hepatoblastoma. It is important for clinicians and pathologists to remember that the liver is also the site of other poorly differentiated and primitive-appearing neoplasms that are distinctive entities from hepatoblastoma.