P63 expression in hydropic abortion and gestational trophoblastic diseases.

Gestational trophoblastic diseases are a group of interrelated diseases of trophoblastic tissue that include partial hydatidiform mole, complete hydatidiform mole, invasive mole, choriocarcinoma, and placental site trophoblastic tumor. P63 is a p53 homologue that, in normal placentas, is expressed in the cytotrophoblast cells. The role of p63 in gestational trophoblastic diseases, however, merits further investigation. Immunohistochemistry with the p63 antibody (clone 4A4) was performed in formalin-fixed paraffin-embedded samples of hydropic abortion (n=10), partial hydatidiform mole (n=12), complete hydatidiform mole (n=12) and choriocarcinoma (n=5). P63 expression was quantitatively assessed as 0 (no stained cells), + (less than 10% positive cells), ++ (10-50% positive cells), and +++ (more than 50% positive cells). The intensity was scored as 0 (absence), + (weak), ++ (moderate), or +++ (strong). Statistical analysis was carried out by the Fisher test. In contrast to the other diagnoses, none of the choriocarcinomas analyzed exhibited p63-positive cells. There was no difference in distribution of p63 positive cells between hydropic abortion, partial hydatidiform mole, and complete hydatidiform mole. Concerning the intensity of immunostaining, there was difference only between partial hydatidiform mole and complete hydatidiform mole. According to our results, p63 might be useful to differentiate a choriocarcinoma from other gestational trophoblastic diseases. Besides, since the intensity of p63 expression was much stronger in partial hydatidiform mole and complete hydatidiform mole than in hydropic abortion, this feature may be helpful in distinguishing these two diagnoses in challenging cases.