Pathology
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Fetopathology and developmental pathology of the embryo and fetus
Marta Ježová, Josef Feit et al.
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Complete mole
Etiology, pathogenesis

Complete mole has a diploid DNA content  —  46 XX, less often 46 XY complete mole is a result of pathologic fertilization.

There are 2 known pathways:

  1. Fertilization of an empty egg (own chromosomes lost) by a single haploid sperm which undergoes duplicatation.
  2. Fertilization of an empty egg by two sperms

All genetic information is paternal in origin.

Macroscopic appearance

An enlarged uterus is filled with voluminous grape  —  like mass. These grape  —  like vesicles are in fact swollen chorionic villi.

No fetus is present.

Clinical signs
  • because of widespread use of ultrasonography most cases of complete mole are now recognized early in first trimster
  • ultrasonography: “snow storm” (multiple echos); fetus is absent
  • Complete mole presents in the early 2nd trimestr, advanced clinical presentations is an exception nowadays:
    • uterine enlargment greater than expected ofr the gestational age
    • vaginal bleeding, anemia
    • spontaneous abortion of the mole
    • markedly elevated hCG level
    • hyperemesis gravidarum
    • early onset pre-eclampsia
    • abortion of molla fragments
    • ovarian theca luetal cysts
  • therapy: evacuation of the mole, hCG monitoring
  • prognosis: 15 – 20% of patients with complete mole develop persistent trophoblastic disease
  • about 2 – 3% of patients with complete mole develop malignant choriocarcinoma
Histology

Typical histologic features are found in the 2nd trimester:

  • all chorionic villi are edematous
  • cistern formation (central cavitation) in many of the swollen villi
  • no blood vessels
  • roundish shape of villi
  • diffuse, circumferential trophoblastic hyperplasia
  • trophoblastic atypia

Histologic features are subtle in the 1st trimester, which makes the diagnosis more difficult (so called early complete mole).

  • slightly swollen villi, no cisterns visible
  • hypercellular bluish stroma, karyorrhexis
  • bulbous round villi
  • focal to diffuse trophoblastic hyperplasia