Very early complete hydatidiform mole.

Recent trends toward early pregnancy ultrasound have led to evacuation of complete hydatidiform moles at a stage before the development of diffuse trophoblast hyperplasia and villous cavitation. Absence of these recognized diagnostic criteria can lead to misdiagnosis and subsequent trophoblastic neoplasia. The authors identified a case of very early complete hydatidiform mole (VECM) on review of a previous curettage specimen when the patient presented 4 weeks later with increasing human chorionic gonadotropin (HCC) titers and the typical histological features of complete mole on a subsequent curettage. DNA studies on this index case and three subsequent similar specimens confirmed the diagnosis of complete hydatidiform mole using polymerase chain reaction (PCR) amplification of eight microsatellite markers on microdissected maternal and villous tissue. VECM were compared with spontaneous abortions and elective terminations of a similar gestational age to develop diagnostic criteria. Five cardinal diagnostic features were identified: redundant bulbous terminal villi, hypercellular villous stroma, a labyrinthine network of vinous stromal canaliculi, focal cytotrophoblast and syncytiotrophoblast hyperplasia on both villi and the undersurface of the chorionic plate, and enlarged hyperchromatic implantation site trophoblast.