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  • Uterine bleeding in first trimester
  • Absence of fetal heart tones and fetal structures
  • Rapid enlargement of the uterus or uterine size greater than anticipated by dates
  • Human chorionic gonadotropin titers greater than expected for gestational age
  • Vaginal expulsion of vesicles
  • Hyperemesis gravidarum
  • Theca lutein cysts
  • Onset of preeclampsia in the first trimester

The spectrum of gestational trophoblastic disease includes hydatidiform moles (complete and partial) and gestational trophoblastic neoplasia comprising invasive moles, choriocarcinomas, and placental-site trophoblastic tumors (PSTT). These tumors are unique in that they develop from an aberrant fertilization event and hence arise from fetal tissue within the maternal host. They are composed of both syncytiotrophoblastic and cytotrophoblastic cells, with the exception of PSTT, which is derived from intermediate trophoblastic cells. In addition to being the first and only disseminated solid tumors that have proved to be highly curable by chemotherapy, they elaborate a unique and characteristic tumor marker, human chorionic gonadotropin (hCG).

Hydatidiform Mole

Hydatidiform mole is the most common form of gestational trophoblastic disease and is benign in nature. Its incidence varies worldwide from 1 in 125 deliveries in Mexico and Taiwan to 1 in 1500 deliveries in the United States. The incidence is higher in women younger than 20 and older than 40 years of age, in nulliparous women, in patients of low socioeconomic status, and in women whose diets are deficient in protein, folic acid, and carotene. Blood group A women impregnated by group O men have an almost 10-fold greater risk of subsequently developing gestational trophoblastic neoplasia than group A women impregnated by group A partners. Furthermore, women with blood group AB tend to have a relatively worse prognosis.

Two distinct forms of hydatidiform mole exist: complete and partial moles. Table 51–1 outlines the clinical, pathologic, and genetic characteristics of both. Cytogenetic studies demonstrate that complete moles are usually euploid, paternal in origin, and sex chromatin-positive–46 XX or 46 XY. They arise when an empty ovum (with an absent or inactivated nucleus) is fertilized by a haploid sperm that duplicates its chromosomes or by two haploid sperm. A partial mole, on the other hand, is triploid–69 XXY (70%), 69 XXX (27%), or 69 XYY (3%)–arising when an ovum with an active nucleus is fertilized by a duplicated sperm or two haploid sperm. Both of these processes result in a homozygous conceptus with a propensity for altered growth.

Hydatidiform mole is thought to arise from extraembryonic trophoblasts. Histologic similarities between molar vesicles and chorionic villi support the view that one is derived from the other. Detailed morphologic studies of hysterectomy specimens containing intact molar pregnancies suggest that transformation of the embryonic inner cell mass at a stage just prior to the laying down of endoderm gives rise to hydatidiform moles. At this stage in embryogenesis, the inner cell mass has the potential to develop into trophoblasts, ectoderm, or endoderm. If normal development is interrupted, such ...

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