p53 expression in gestational trophoblastic disease.

The p53 expression of normal trophoblasts (11 cases), partial moles (11 cases), complete moles (19 cases), and gestational choriocarcinoma (eight cases) were studied. We found that p53 is frequently expressed in gestational choriocarcinoma and in hydatidiform moles (mainly cytotrophoblasts), whereas syncytiotrophoblasts are generally spared. This finding supports the view that p53 expression is a reflection of proliferative capacity of cells rather than an indicator of neoplastic or malignant transformation. The greater p53 expression observed in complete moles as compared with partial moles is in keeping with the more pronounced trophoblastic hyperplasia and proliferative activity of complete moles. More interesting was the observation that p53 expression was also noted in normal trophoblasts, secretory endometrial glands, and decidual cells of the stroma. Therefore, it appears that the immunohistochemical expression of p53 can occur in a variety of situations, including neoplastic, proliferative, and nonproliferative conditions. Although p53 mutations are often the basis of excessive accumulation of mutant p53 protein in malignancies, other mechanisms may be involved in nonneoplastic conditions. These findings emphasize the need for caution in the interpretation of immunohistochemical expression of p53 protein.