Gestational trophoblastic neoplasia (choriocarcinoma)

Definition

• Gestational trophoblastic neoplasia (GTN) comprises the malignant, non-molar forms of gestational trophoblastic disease: invasive mole, choriocarcinoma, epithelioid trophoblastic tumour (ETT) and placental site trophoblastic tumour (PSTT).
• Choriocarcinoma is a rare, aggressive neoplasm; the gestational form arises after a hydatidiform mole, a normal pregnancy or a miscarriage.

Classification

Persistent trophoblastic disease

• Criteria for persistent trophoblastic disease include a beta-hCG plateau over three weeks or a/an rise over two weeks.

• Classification uses the anatomical FIGO stages I–IV together with the modified WHO prognostic score; a score of 0–6 is regarded as low risk and 7 or more as high risk.

Occurrence & epidemiology

Epidemiology

• The overall incidence of GTN is about 1 in 40,000 pregnancies.
• After a complete mole about 15% develop an invasive mole and 5% metastatic disease; choriocarcinoma follows 2–3% of hydatidiform moles, more often complete than partial moles.
• Most choriocarcinomas follow a molar pregnancy, miscarriage or ectopic pregnancy; about one quarter are preceded by a full-term pregnancy.

Clinical features

Clinical features and complications

• The leading symptoms of trophoblastic disease are vaginal bleeding and a rapidly enlarging uterus; persistent bleeding after childbirth raises suspicion of choriocarcinoma.
• Choriocarcinoma often first presents with metastases to the lungs, liver or brain, for example with neurological symptoms; it may arise weeks to years after the causative pregnancy.

Histology

• Choriocarcinoma is a malignant tumour of the trophoblastic epithelium: columns and sheets of trophoblastic tissue invade myometrium and blood vessels, with haemorrhage and necrosis.
• Unlike hydatidiform mole and invasive mole, in which villous structures persist, choriocarcinoma lacks villi.

Diagnosis

• Postmolar GTN is usually identified from the hCG course: an hCG plateau over 3 weeks, a rise over 2 weeks (3 values) or hCG still detectable 6 months after the mole; in choriocarcinoma beta-hCG is typically high.
• Staging includes CT of the chest, abdomen and pelvis; pelvic ultrasound or MRI shows the uterine tumour, and metastases outside the lungs usually occur only after lung metastases are established.

Keep learning in the app

Further reading (selection)

1. StatPearls: Gestational Trophoblastic Disease (NCBI Bookshelf)
2. MSD Manual Professional Edition: Gestational Trophoblastic Disease
3. DocCheck Flexikon, Blasenmole

Cross-references