P53 PROTEIN EXPRESSION IN HEPATOBLASTOMA - AN IMMUNOHISTOCHEMICAL INVESTIGATION

Mutations of the p53 tumor suppressor gene with immunohistochemically detectable expression of p53 protein have been described in many diffe rent malignant tumors. In this study, 12 hepatoblastomas of various su btypes were investigated immunohistochemically with a monoclonal antib ody for the expression of p53 protein. Immunoreactivity for p53 protei n was found in both small cell tumors investigated and in embryonal ar eas in two out of eight tumors, but not fetal (eight tumors) or mesenc hymal (four tumors) areas. The findings show that immunohistochemicall y detectable expression of p53 protein, which generally indicates muta tion of the gene, may also be present in hepatoblastoma. The finding o f p53 protein immunoreactivity in both of the small cell tumors but no ne of the fetal areas is consistent with a proposal in the literature concerning the histogenesis and differentiation of the various subtype s-that fetal hepatoblastoma is the most well-differentiated and small cell hepatoblastoma the least well-differentiated subtype.