Gestational trophoblastic neoplasia pathophysiology

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Template:Choriocarcinoma Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Monalisa Dmello, M.B,B.S., M.D. [2]

Pathophysiology

A hydatidiform mole is characterized by a conceptus of hyperplastic trophoblastic tissue attached to the placenta. The conceptus does not contain the inner cell mass (the mass of cells inside the primordial embryo that will eventually give rise to the fetus). The hydatidiform mole can be of two types: a complete mole, in which the abnormal embryonic tissue is derived from the father only; and a partial mole, in which the abnormal tissue is derived from both parents.

  • Complete moles usually occur when an empty ovum is fertilized by a sperm that then duplicates its own DNA (a process called androgenesis). A 46, XY genotype may occur when 2 sperm (one 23, X and the other 23, Y) fertilize an empty egg.[1]). Their DNA is purely paternal in origin (since all chromosomes are derived from the sperm), and is diploid. Ninety percent are 46,XX, and 10% are 46,XY. In a complete mole, the fetus fails to develop.
  • Partial moles can occur if a normal haploid ovum is fertilized by two sperm, or, if fertilized by one sperm, if the paternal chromosomes become duplicated. Thus their DNA is both maternal and paternal in origin. They can be triploid (e.g. 69 XXX, 69 XXY) or even tetraploid.

Choriocarcinoma of the placenta during pregnancy is preceded by:

Genetics

  • Invasive mole- diploid or aneuploid karyotype
  • Choriocarcinomas- aneuploid karyotype

Gross Pathology

  • Dark, shaggy, focally hemorrhagic & friable/necrotic-appearing
  • Invasive border

Microscopic Pathology

Gestational Trophoblastic Neoplasias[2]

Types of Gestational Trophoblastic Neoplasia Histopathological features

Invasive mole

  • The lesions are characterized by hyperplasia of cytotrophoblastic and syncytial elements and persistence of villous structures
  • The lesions are characterized by trophoblastic invasion of the myometrium with identifiable villous structures

Choriocarcinoma

  • The lesions are characterized by columns and sheets of trophoblastic tissue invading uterine muscle and blood vessels

Placental-site trophoblastic tumor

  • The tumor arising from the placental implantation site and resembles an exaggerated form of syncytial endometritis
  • Trophoblastic cells infiltrate the myometrium, and there is vascular invasion

Epithelioid trophoblastic tumor

  • The tumor has a monomorphic cellular pattern of epithelioid cells and may resemble squamous cell cancer of the cervix when arising in the cervical canal

References

  1. Woo J, Hsu C, Fung L, Ma H (1983). "Partial hydatidiform mole: ultrasonographic features". Aust N Z J Obstet Gynaecol. 23 (2): 103–7. PMID 6578773.
  2. Cellular Classification of Gestational Trophoblastic Disease. National Cancer Institute. http://www.cancer.gov/types/gestational-trophoblastic/hp/gtd-treatment-pdq/#section/_5 Accessed on October 8, 2015

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