Gross / macroscopic variations and conditions

Fetal membranes

Chorionic cysts

Last author update: 1 October 2011
Last staff update: 28 October 2020

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PubMed Search: Chorionic cysts placenta

Mandolin S. Ziadie, M.D.
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Cite this page: Ziadie MS. Chorionic cysts. website. Accessed September 21st, 2023.
Definition / general
  • Fluid filled spaces in the placental membranes, beneath the chorionic plate or within cell islands or septa
  • May be associated with chronic uterine hypoxia (Pediatr Dev Pathol 2011;14:1)
  • Thought to be due to ischemia and degeneration
Gross description
  • When visible grossly, cysts are usually small ( < 3 cm) and bulge into the amnionic cavity from the fetal surface
  • Differential diagnosis of grossly visible cysts includes partial moles
Microscopic (histologic) description
  • Spaces filled with eosinophilic proteinaceous material and lined by extravillous trophoblastic cells
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