Other nonneoplastic lesions

Ectopic decidual reaction

Last author update: 1 February 2017
Last staff update: 21 November 2022 (update in progress)

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PubMed Search: Ectopic decidual reaction

Aurelia Busca, M.D., Ph.D.
Carlos Parra-Herran, M.D.
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Cite this page: Busca A, Parra-Herran C. Ectopic decidual reaction. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarynontumorectopicdecidual.html. Accessed June 5th, 2023.
Definition / general
  • Presence of ectopic decidualized uterine stromal cells in the ovary
  • Ectopic decidua or ovarian deciduosis
  • Ectopic decidua has been described in the cervix, ovary and fallopian tube; also peritoneal surface, appendix, bladder, small and large intestine, mesentery, lymph nodes
  • Often an incidental finding in surgical specimens or discrete nodule / mass discovered during caesarean section
Radiology description
Case reports
  • Benign entity, no further treatment necessary; usually regresses 4 - 6 weeks postpartum
  • If mass forming and imaging shows worrisome features for malignancy, the lesion is excised to establish the correct diagnosis
Gross images

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Ectopic decidual reaction

Microscopic (histologic) description
  • Large polygonal cells with abundant eosinophilic cytoplasm, bland nuclei and visible nucleoli
Microscopic (histologic) images

Contributed by Aurelia Busca, M.D., Ph.D.

Deciduosis of ovarian stroma

Areas of deciduosis

Ovarian surface adhesions with deciduosis

Images hosted on other servers:
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Left decidualized ovarian mass

Negative stains
Differential diagnosis
  • Endometriosis, which can also undergo decidualization during pregnancy
  • Epithelial ovarian neoplasm when mass forming
  • Peritoneal mesothelioma or peritoneal carcinomatosis when there is additional involvement of peritoneal surface
Additional references
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