Definition and epidemiology
Hydatidiform mole is a type of gestational trophoblastic disease, a condition caused by proliferation of trophoblasts. It’s characterised by transformation of terminal villi into vesicles filled with clear viscid material, making them look like grapes.
Hydatidiform moles are usually benign, but malignant in 15 – 25% of cases. In this case, it’s called a persistent trophoblastic neoplasia (PTN).
- Old age
- Previous gestational trophoblastic disease
- Pathologic eggs
- Vitamin A deficiency
- Dietary protein deficiency
We can distinguish complete and partial hydatidiform moles. Moles are partial if normal placental tissues or foetal structures are present. If there are no such tissues present, it’s complete.
Complete moles are diploid and are the result of paternal disomy. A sperm cell (23X) duplicates itself after fertilisation of an empty egg, which forms the 46XX mole. It can also occur if two sperm cells fertilise an egg simultaneously, but that is very rare.
Partial moles are triploid. They occur when a normal egg is fertilised by two sperms simultaneously, forming either 69XXX, 69XXY, or 69XYY.
Complete moles are more likely to become malignant. Moles produce hCG, and more than what’s normal.
The patient considers themselves to be pregnant, due to the hCG-mediated symptoms of pregnancy like amenorrhoea and nausea. Symptoms of pregnancy like nausea may be more severe than what’s normal. The patient may also experience bright red spotting or dark brown vaginal discharge.
In cases of twin pregnancies where only one placenta is a mole, the other baby can be born normally.
Diagnosis and evaluation
The ultrasound is enlarged compared to the gestational age. Bilateral theca lutein cysts of the ovary may be present.
The ultrasound picture of the mole itself is very characteristic, it’s described as being similar to snowfall.
The hCG concentration is significantly higher than normal, and no foetal vital signs can be detected.
The uterus should be evacuated as soon as possible. This is achieved by dilation of the cervix, followed by suction curette and standard curette. Oxytocin infusion is used to prevent bleeding.
If a mole is diagnosed over the age of 40, due to the high malignant potential, total abdominal hysterectomy should be performed.
After surgical removal, pathological evaluation is necessary to confirm the diagnosis.
Serum β-hCG and SP1 must be monitored in the time after the treatment to make sure there is no recurrence. Normalisation of the values may take months. If the values stop decreasing, or they start increasing, a recurrence is likely. Recurrence should be treated with methotrexate.
B21. Cervical cancer; FIGO classification and therapy
B23. Gestational throphoblast neoplasia (invasive mole, choriocarcinoma); diagnosis and therapy