Endometrial hyperplasia

Author: Carlos Parra-Herran, M.D. (see Authors page)

Revised: 17 September 2018, last major update August 2016

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Endometrial hyperplasia [title]

Cite this page: Parra-Herran, C. Endometrial hyperplasia - general. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/uterusendometrialhyperplasiageneral.html. Accessed October 22nd, 2018.
Definition / general
  • Definition: Proliferation of endometrial glands with an increase in the gland to stroma ratio compared to proliferative endometrium (> 1:1, glands represent more than 50% of the surface area)
  • The term "endometrial hyperplasia" includes lesions ranging from reversible glandular proliferations to direct cancer precursors (Semin Diagn Pathol 2010;27:199)
  • Incidence: simple - 142 / 100,000 woman-years, complex - 213 / 100,000 woman-years (both in the early 50s); atypical - 56 / 100,000 woman-years (in early 60s) (Am J Obstet Gynecol 2009;200:678)
  • Comparing curettage to subsequent hysterectomy, false positive rate of 1.8% and false negative rate of 13.2%; less accurate if use Pipelle endometrial sampler (Eur J Obstet Gynecol Reprod Biol 2011;159:172)

  • Previously classified based on WHO as simple vs complex, nonatypical vs atypical or EIN systems (J Gynecol Oncol 2010;21:97) - current WHO classification incorporates both systems and simplifies the terminology
  • Previous WHO system (endometrial hyperplasia) suffers from poor diagnostic reproducibility (Am J Surg Pathol 2008;32:691)
  • Prolonged estrogenic stimulation with reduced progestational activity (usually near menopause or associated with anovulatory cycles)
  • Polycystic ovarian disease (Stein-Leventhal syndrome)
  • Ovarian granulosa cell tumors (functional)
  • Ovarian cortical stromal hyperplasia
  • Estrogen replacement therapy without progestational agents (Ann Epidemiol 2009;19:1)
  • Also associated with higher body mass index and obesity (J Reprod Med 2011;56:110)
  • Progression from normal to simple to complex hyperplasia associated with reduced levels of von Hippel-Lindau mRNA and protein (Int J Gynecol Cancer 2011;21:430)
Diagrams / tables

Images hosted on PathOut server:

Contributed by Carlos Parra-Herran, M.D.
Prognostic factors
  • Usual predecessor to endometrial carcinoma, particularly younger women or those with well differentiated endometrioid adenocarcinoma, although most with hyperplasia do NOT develop carcinoma
  • Risk of developing carcinoma is greater with atypical hyperplasia and EIN
  • For nonatypical endometrial hyperplasia, risk was 1.2% at 4 years, 1.9% at 9 years, 4.6% at 19 years after diagnosis; for atypical hyperplasia, risk was 8.2% at 4 years, 12.4% at 9 years, 27.5% at 19 years (J Clin Oncol 2010;28:788)
  • Focal gland crowding, that does not fulfill all criteria for EIN, carries substantial risk of EIN and occasionally malignancy (Mod Pathol 2010;23:1486)
Gross description
  • Lush, polypoid endometrium
Gross images

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Endometrial hyperplasia

Microscopic (histologic) description
Microscopic (histologic) images

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Contributed by Carlos Parra-Herran, M.D.

Benign endometrial hyperplasia

Endometroid intraepithelial neoplasia

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Squamous morules

Differential diagnosis
Additional references