[Gestational trophoblastic diseases. Classification, epidemiology and genetic data].

Gestational trophoblastic diseases amalgamate several entities with a common denominator which is a hypersecretion of hCG: complete mole, invasive or not, partial mole or triploid syndrome, gestational trophoblastic carcinoma and trophoblastic carcinoma from the implantation site. These entities differ by their origins, their morphology, their evolution and their treatments. Complete moles are diploid and in 80% of cases, chromosomes are only from paternal origin (diandry or dispermy). Their evolution is unpredictable whatever the molecular biology or cytogenetical methods are. Partial moles, generally triploid, are much more frequent (10-20% of miscarriages) than the number of cases diagnosed during the pregnancy. In 85% of cases, two sets of chromosomes are of paternal origin. The gestational trophoblastic carcinoma is diploid and its genetic material comes from both parents. This probably excludes a direct filiation between complete mole and gestational trophoblastic carcinoma. The trophoblastic tumor from the implantation site comes from the trophoblast of the implantation site which explain why its evolution and its prognosis are totally distinct from the previous one. In this report, we successively discuss the natural history of gestational trophoblastic diseases, their epidemiology and the genetic data explaining their origins.