ESSENTIALS OF DIAGNOSIS
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
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 (PSTTs). 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 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 beta-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 53–1 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 2 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 2 haploid sperm. Both of these processes result in a homozygous conceptus with a propensity for altered growth.
Table 53–1.Comparison of complete and partial hydatidiform moles. ||Download (.pdf) Table 53–1. Comparison of complete and partial hydatidiform moles.
| ||Complete ||Partial |
|Karyotype ||Diploid (46,XX or 46,XY) ||Triploid (69,XXX or 69,XXY) |
|Fetus ||Absent ||Often present |
|Villi ||Diffusely hydropic ||Focally hydropic |
|Trophoblasts ||Diffuse hyperplasia ||Mild focal hyperplasia |
|Implantation-site trophoblast ||Diffuse atypia ||Focal atypia |
|P57, PHLDA2 immunostaining1 ||Negative ||Positive |
|Fetal RBCs ||Absent ||Present |
|β-hCG (mIU/mL) ||High (>50,000) ||Slight elevation ...|