Hydatidiform mole: clinicopathologic associations with the development of postevacuation trophoblastic disease.

Clinical information and histopathologic material for 165 patients with hydatidiform mole referred to the John I. Brewer Trophoblastic Disease Center of Northwestern University Medical School during one year were reviewed in order to identify characteristics more likely to be associated with the development of gestational trophoblastic tumors. Twenty-nine patients (18%) required chemotherapy for invasive mole or choriocarcinoma. Patients with uterine enlargement beyond that expected for dates and patients with ovarian theca-lutein cysts were much more likely to require treatment after molar evacuation (47% vs. 18% and 40% vs. 16%, respectively). There was no correlation between the initial human chorionic gonadotropin level, gestational age, uterine size per se, maternal age or gravidity and the subsequent clinical course. Histologically, the following factors were associated with an increased incidence of postmolar gestational trophoblastic tumor: (1) progressive nuclear atypia (26.7% if atypia present vs. 40% if absent); (2) necrosis and hemorrhage (39.1% if extensive vs. 12.8% if limited); (3) decreased trophoblast maturation (48% if less than 20% mature vs. 8.7% if greater than or equal to 20% mature); (4) trophoblast proliferation (50% if marked vs. 13.9% if limited); (5) increased ratio of cytotrophoblast to syncytium (33.3% if greater than 1 vs. 6.4% if less than 1); and (6) absence of Nitabuch's layer (21.4% if absent vs. 11.6% if present). Hydatidiform moles which demonstrate clinical or histopathologic evidence of excessively abnormal proliferative activity, as indicated by these features, are more likely to develop invasive mole or choriocarcinoma and should be considered for prophylactic chemotherapy.