Gestational Trophoblastic Neoplasia (GTN)
GTN represents a spectrum of malignant trophoblastic diseases that can follow any type of pregnancy. It is characterized by the persistence of β-hCG after evacuation of a hydatidiform mole or, less commonly, after term birth or abortion.
Clinical Classification
- Invasive Mole: Locally invasive; most commonly follows a complete hydatidiform mole.
- Choriocarcinoma: Highly malignant, rapidly growing, and early hematogenous spread (especially to lungs and brain).
- Placental Site Trophoblastic Tumor (PSTT): Rare, slow-growing, produces low levels of β-hCG.
Diagnostic Criteria (FIGO)
| Scenario | Diagnosis of GTN |
|---|---|
| Plateau | β-hCG plateau for 4 measurements over 3 weeks. |
| Rise | β-hCG rise of ≥ 10% for 3 measurements over 2 weeks. |
| Persistence | β-hCG remains detectable for 6 months after evacuation. |
High-Yield Exam Pearl:
- Staging: GTN is staged using the FIGO system (anatomic stage + risk score). Low-risk patients are effectively treated with single-agent chemotherapy (Methotrexate or Actinomycin D).
- Histology: Choriocarcinoma is unique because it lacks villi and is composed of sheets of syncytiotrophoblasts and cytotrophoblasts.