Gross/Macroscopic Variations and Conditions

Fetal Membranes

Chorionic cysts

Topic Completed: 1 October 2011

Minor changes: 28 October 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Chorionic cysts placenta

Mandolin S. Ziadie, M.D.
Page views in 2020: 2,847
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Cite this page: Ziadie MS. Chorionic cysts. website. Accessed December 8th, 2021.
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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