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Non tumor

Pregnancy-related changes

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 26 March 2012, last major update September 2011
Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.

See also Arias-Stella reaction


● These changes are similar with intrauterine pregnancy, ectopic pregnancy and progesterone therapy


● Maternal portion of placenta composed of endometrial lining during pregnancy; due to influence of progesterone (Wikipedia)
● Cells are highly characteristic: sheets of large polygonal cells with abundant cytoplasm, minimal atypia

Gestational hyperplasia

Gross description: lush decidua, placental fragments, gestational sac
Micro description: early - prominent glandular secretion, stromal edema and predecidual reaction, all simultaneous; implies fertilized ovum has implanted; later changes - glands are tubular, not coiled
● Glandular cells may have inclusion-like cleared chromatin resembling HSV infection, due to replacement of chromatin by fine filamentous network that is immunoreactive for biotin (J Clin Pathol 1997;50:153); may see intermediate trophoblasts or villi
DD: late secretory changes in cycling endometrium

Placental site nodules

● Also called implantation site reaction
● Uncommon; benign; usually regresses after delivery or abortion (Indian J Pathol Microbiol 2009;52:240)
Micro description: numerous chorionic-type extravillous (intermediate) trophoblasts with large, atypical nuclei arranged in a syncytium, often with mitotic figures that may invade blood vessels (to keep them patent during pregnancy); also cytotrophoblasts and syncytiotrophoblasts, chronic inflammatory cells
Positive stains: hPL (intermediate trophoblasts), hCG (syncytiotrophoblasts, cytotrophoblasts), keratin
Differential diagnosis:
- Exaggerated placental site: different type of intermediate trophoblasts, no mitotic activity, different staining pattern, Hum Pathol 1999;30:687)
- Leiomyosarcoma: keratin negative, negative for hPL and hCG
- Placental site trophoblastic tumor: large masses of intermediate trophoblasts, mitotic activity, no villi, (Am J Surg Pathol 1990;14:1001)
- Choriocarcinoma: laminar pattern of syncytiotrophoblasts and cytotrophoblasts with extensive hemorrhagic necrosis, no villi

Gross images

Fetus within uterus

Micro images

Decidua: various images

Gestational endometrium: various images


Placental site nodule: various images

Gestational endometrium #1, #2, #3

End of Uterus > Non tumor > Pregnancy-related changes

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