Complete hydatidiform mole. Comparison of clinicopathologic features, current and past

To investigate whether changes have occurred in the pathologic and clinical features of complete molar gestation in recent years.

Twenty-three contemporary complete hydatidiform moles (1994-1997) and 20 historical complete moles (1969-1975) were compared regarding clinical features (gestational age at evacuation, maternal age, preevacuation diagnosis and persistence) and pathologic findings (volume of tissue, presence of gross cisterns, maximal villous size, percent of cavitated villi, percent of villi exhibiting circumferential trophoblast hyperplasia, and presence of necrosis and primitive stromal features).

Contemporary complete moles were evacuated at an earlier mean gestational age (8.5 vs. 17.0 weeks, P = .00008). Histologically, contemporary complete moles had less circumferential trophoblastic hyperplasia (39% vs. 75% of villi, P = .03), a smaller mean maximal villous diameter (5.7 vs. 8.2 mm, P = .001), more primitive villous stroma (70% vs. 10% of cases, P = .0003) and less global necrosis (22% vs. 54% of cases, P = .02).

These striking morphologic differences indicate that pathologic findings in complete molar gestations have changed significantly over the past several decades due to the current practice of very early uterine evacuation. Contemporary complete moles are often characterized by subtle morphologic alterations that may result in their misclassification as partial moles or nonmolar spontaneous abortions. It is important for pathologists to recognize the distinctive histopathologic features of early complete hydatidiform mole.