Nonneoplastic placental conditions and abnormalities


Villitis of unknown etiology

Last author update: 1 October 2011
Last staff update: 29 October 2020

Copyright: 2002-2022,, Inc.

PubMed Search: Placental villitis of unknown etiology

Mandolin S. Ziadie, M.D.
Page views in 2021: 3,340
Page views in 2022 to date: 3,062
Cite this page: Ziadie MS. Villitis of unknown etiology. website. Accessed December 9th, 2022.
Definition / general
  • Chronic inflammatory cells within stroma of chorionic villi
  • No causative organism
  • Infiltrating cells have been shown to be maternal T cells, suggesting that this is an immune mediated disease
  • Associated with fetal growth restriction, premature delivery and stillbirth (more common with recurrent disease)
  • Seen in 3 - 5% of placentas with greater incidence (25%) in small for gestational age newborns
  • Focal (low grade): small clusters of villi ( < 10) on a single slide
  • Multifocal (low grade): small clusters of involved villi ( < 10) on multiple slides
  • Patchy (high grade): larger clusters of villi ( > 10) on multiple slides
  • Diffuse (high grade): large clusters of villi ( > 10) on all slides
Microscopic (histologic) description
  • Lymphocytes and macrophages within the villous stroma, sometimes with granulomas and giant cells
  • May be accompanied by chronic deciduitis with plasma cells, chronic chorioamniotis, perivillous fibrin, avascular villi and rarely with chronic intervillositis
Back to top
Image 01 Image 02