Gestational trophoblastic disease

Gestational trophoblastic disease (GTD) results from abnormal proliferation of trophoblastic tissue, and encompasses a wide spectrum which includes :

• hydatidiform mole
  • complete mole
  • partial mole
• invasive mole ~10%
• choriocarcinoma (gestational choriocarcinoma) ~1%
• placental site trophoblastic tumour (PSTT)
• epithelioid trophoblastic tumour (ETT)

Demographics and clinical presentation

Women older than 40 years and younger than 20 may be at higher risk.

In a broad very sense patients may present with

• a uterus larger than dates
• abnormally high beta HCG
• hyperemesis
• hypertension
• theca-lutein cysts

Pathology

A common characteristic of all GTD's is the abnormal proliferation of trophoblast, but different components predominate in different tumours.

Classification

• hydatidiform mole : see sub article on hydatidiform mole
  • complete (CHM) : see sub article on complete hydatidiform mole
    • commonest (up to 80%) manifestation of GTD
    • 46XX or 46XY : paternal chromosomes only
    • no fetus
    • beta HCG markedly elevated
    • atypia of cells present
    • treatment involves
      • curettage
      • follow up urinary beta HCG for 6 - 12 months
      • ? hysterectomy in older women
    • may progress to 
      • invasive mole : ≈ 15 % 
      • choriocarcinoma : ≈  5 %  
  • partial (PHM) : see sub article on partial hydatidiform mole
    • 69XXX or 69XXY (paternal and maternal chromosomes)
    • may have a fetus or components
    • beta HCG moderately elevated
    • no cellular atypia
• invasive mole : see sub article on invasive mole
  • distorts uterine zonal structures
  • boundaries with the tumour and myometrium are irregular and indistinct ³
  • may also invade parametrial tissue and blood vessels ⁴
• choriocarcinoma (gestational choriocarcinoma) : 
  • may look identical to hydatidiform mole
  • can appear to have less vascularity than an invasive mole
  • higher beta HCG levels even than a complete mole
  • solid component with visualised invasion
  • tends to invade myometrium through venous plexuses
    • patients often can however present with multiple metastases without an easily identified primary, as it can often be small in an otherwise normal placenta. 
    • only 50 % of choriocarcinoma arises from a known molar pregnancy
    • 30 % following miscarriage and 
    • 20 % following normal pregnancy.
  • metastases can occur to
    • lungs : ~ 80%
    • vagina : ~ 30%
    • pelvis : 20% 
    • liver and brain : ~ 10% (each ?)
• placental site trophoblastic tumour (PSTT) : see sub article on placental site trophoblastic tumour
  • rare form
  • produces small amounts of betaHCG
• epithelioid trophoblastic tumour (ETT) ⁹ : see sub article on epithelioid trophoblastic tumour
  • extremely rare form

See also

• molar pregnancy