Gestational Trophoblastic Disease

GTD Spectrum - Trophoblast Tales

Gestational Trophoblastic Disease (GTD) encompasses a spectrum of disorders arising from abnormal proliferation of placental trophoblasts. It ranges from premalignant to malignant conditions.

WHO Classification:

• Hydatidiform Mole
  • Complete Mole (CHM)
  • Partial Mole (PHM)
• Invasive Mole
• Choriocarcinoma
• Placental Site Trophoblastic Tumor (PSTT)
• Epithelioid Trophoblastic Tumor (ETT)

⭐ GTD originates from abnormal proliferation of placental trophoblast cells, the cells that normally develop into the placenta during pregnancy.

Molar Pregnancies - Grape Expectations

Hydatidiform Mole (HM), a key Gestational Trophoblastic Disease (GTD), includes Complete (CM) and Partial (PM) types.

⭐ Complete mole typically has a 46,XX karyotype, with all chromosomes being of paternal origin.

Malignant GTD - When Trophoblasts Attack

Malignant Gestational Trophoblastic Diseases (GTD) represent a spectrum of aggressive trophoblastic proliferations.

• Invasive Mole:
  • Invades myometrium.
  • Persistent ↑ hCG levels post-molar evacuation.
  • Chorionic villi present.
• Choriocarcinoma:
  • Malignant proliferation of cytotrophoblasts & syncytiotrophoblasts.
  • NO chorionic villi.
  • Markedly ↑ hCG.
  • Early hematogenous spread (lungs, vagina).

  ⭐ Choriocarcinoma is highly aggressive and metastasizes early via bloodstream, most commonly to the lungs and vagina.

• Placental Site Trophoblastic Tumor (PSTT):
  • Arises from intermediate trophoblasts at placental site.
  • Relatively ↓ hCG levels; hPL positive.
  • Late metastasis (lymphatic/hematogenous).
• Epithelioid Trophoblastic Tumor (ETT):
  • Rare, nodular proliferation of intermediate trophoblasts.
  • Can mimic PSTT or squamous cell carcinoma.
  • Variable hCG levels.

GTD Detective & Doctor - Spot, Stage, Solve

Spot GTD:

• Clinical: Vaginal bleeding, Uterine size > dates, Hyperemesis, Pre-eclampsia <20wks, Hyperthyroidism.

Key Investigations:

• Serial quantitative β-hCG (crucial for monitoring).
• Ultrasound (e.g., "snowstorm" for complete mole).

GTN Diagnosis (Post-Molar hCG Criteria):

• Plateau: 4 values (±10%) over 3 wks (days 1, 7, 14, 21).
• Rise: >10% for 3 values over 2 wks (days 1, 7, 14).
• Persistence: Detectable β-hCG 6 months post-evacuation.
• Histologic diagnosis (e.g., choriocarcinoma).

Stage & Solve GTN:

• FIGO 2000 anatomic staging. Prognostic risk score based on:
  • Antecedent pregnancy, Interval from index pregnancy
  • Pre-treatment hCG level, Largest tumor size
  • Metastasis (site & number), Previous failed chemotherapy
• Score: Low risk ≤6; High risk ≥7.

⭐ Serial β-hCG monitoring is the cornerstone for diagnosis of GTN, assessment of treatment response, and detection of relapse.

High‑Yield Points - ⚡ Biggest Takeaways

• Complete moles: 46,XX (all paternal), no fetal parts, markedly ↑↑ hCG, higher choriocarcinoma risk.
• Partial moles: Triploid (e.g., 69,XXY), fetal parts present, hCG less elevated.
• hCG is the essential tumor marker for GTD diagnosis and follow-up.
• Choriocarcinoma: Highly malignant, early metastasis (lungs), excellent chemotherapy response.
• Invasive mole: Invades myometrium, persistent ↑ hCG post-evacuation.
• PSTT: Rare, from intermediate trophoblasts, produces hPL, often chemoresistant.