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Gestational
Trophoblastic Disease
Chapter 50
Mitchell I. Edelson, MD
❍ What are the histologically distinct disease entities encompassed by the general terminology of gestational
trophoblastic neoplasia (GTN)?
(1) Hydatidiform moles (complete and partial).
(2) Invasive mole.
(3) Gestational choriocarcinoma.
(4) Placental site trophoblastic tumors (PSTTs).
❍ Describe the characteristics of trophoblastic cells (both normal and abnormal) that allow them to
metastasize.
Trophoblastic cells do not express transplantation antigens (HLA and ABO), allowing them to escape from
maternal immunologic rejection. They are thus able to invade into maternal decidua, vessels, and myometrium.
Embolization of trophoblastic cells from the endometrial sinuses into the maternal venous system occurs
continuously. The maternal pulmonary circulation is responsible for filtering out these cells and thus preventing
them access to the system circulation.
❍ What is GTD?
This is the term used to describe the various diseases with the potential to invade normal tissue and metastasize.
This would encompass choriocarcinoma, invasive mole, postmolar GTD, and PSTTs.
❍ What is the incidence of the various forms of GTD in the United States?
Approximately 1 in 600 therapeutic abortions and 1 in 1500 pregnancies.
❍ What is the incidence of hydatidiform moles in the general population?
The incidence of complete hydatidiform moles is estimated to be between 0.26 and 13 per 1000 pregnancies.
Asian and Latin American women share a twofold increase in risk compared with other populations.