ABSTRACT
Over 80% of hydatidiform moles remain benign but about 15% (untreated) will progress to become locally invasive and 2-3% will develop into choriocarcinomas. Choriocarcinoma may also arise without passing through the preceding stages and the total incidence (in the Western world) is about one in 40,000 (that is, about 50% arise de novo after a normal pregnancy).
