Hydatidiform mole

Tip

Hydatidiform mole: need sperm + oocyte.
Teratoma: just oocyte.

Epidemiology

Etiology

Tip

The terms "partial" and "complete" refer to the extent of abnormal tissue growth and the presence or absence of fetal tissue. In a complete mole, no normal tissue is present, whereas in a partial mole, there may be some but it’s still non-viable.

Complete mole

Fertilization of an empty egg that does not carry any chromosomes by a single sperm
The (physiological) haploid chromosome set contributed by the sperm is subsequently duplicated.
Fetal karyotypes
- 46XX (more common; ∼ 90% of cases)
- 46XY (less common; ∼ 10% of cases)

Partial mole

Fertilization of an egg containing a haploid set of chromosomes with two sperms
Fetal karyotypes
- 69XXY
- 69XXX

Pathophysiology

Clinical features

Vaginal bleeding during the first trimester
Uterus size greater than normal for gestational age
Pelvic pressure or pain
Passage of vesicles with grape-like appearance
β-hCG-mediated endocrine conditions
- Theca lutein cysts
- Preeclampsia (before the 20th week of gestation)
- Hyperemesis gravidarum
- Hyperthyroidism: Very high amounts of hCG may lead to hyperthyroidism because the α-subunit of hCG structurally resembles TSH.

Diagnostics

DDx

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Feature	Choriocarcinoma	Hydatidiform Mole	Teratoma
Definition/Origin	Malignancy of cytotrophoblasts & syncytiotrophoblasts; no villi.	Abnormal proliferation of trophoblasts with edematous villi.	Germ cell tumor with derivatives from 2-3 germ layers (e.g., teeth, hair).
Fertilization	Yes	Yes	No
Karyotype	Typically aneuploid (abnormal chromosome number).	Complete Mole: 46,XX (or 46,XY); entirely paternal DNA. Partial Mole: 69,XXY (or XXX, XYY).	46,XX (for mature ovarian teratomas).
Malignancy	Highly malignant and metastatic.	Benign, but can progress to choriocarcinoma.	Usually benign (mature), can be malignant (immature).
Clinical / hCG	Presents with mets (lungs, brain), abnormal bleeding. Very high hCG.	Uterine bleeding, size > dates, preeclampsia <20 wks. Very high hCG (complete).	Often asymptomatic or causes mass effect (e.g., ovarian torsion). hCG usually normal.