Endometrial metaplasia

Topic Completed: 1 March 2012

Minor changes: 5 August 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed search::endometrial metaplasia uterus

Subtypes: clear cell, eosinophilic (oxyphilic), intestinal, mucinous, papillary, squamous, stromal, syncytial, tubal

Nat Pernick, M.D.
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Cite this page: Pernick N. Endometrial metaplasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/uterusmetaplasia.html. Accessed August 12th, 2020.
Definition / general
  • Often due to hormonal or irritative stimuli (J Clin Pathol 2011;64:97, Am J Surg Pathol 1980;4:525)
  • Must evaluate metaplasia separately from hyperplasia
  • Tends to be associated with adenocarcinoma and is more common in women at high risk for endometrial carcinoma

Clear cell metaplasia
  • Tall cells, apical nuclei and clear cytoplasm; no atypia
  • Clear cell change by itself is nonspecific
  • Case reports: with atypical endometrial hyperplasia (Ann Diagn Pathol 2003;7:381)
  • DD: clear cell adenocarcinoma

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Atypical endometrial hyperplasia with clear cell change

Eosinophilic (oxyphilic) metaplasia
  • Also called eosinophilic cell change
  • Estrogen induced, resembles atypical hyperplasia except there is no atypia
  • Nonspecific and very common; associated with mucinous metaplasia and ciliated (tubal) change (Mod Pathol 2005;18:1243)
  • MUC5AC+

Intestinal metaplasia
  • Rare

Micro images

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Intestinal metaplasia

Positive stains

Mucinous metaplasia<
  • Resembles endocervical mucosa (Int J Gynecol Pathol 1983;1:383); benign features
  • Associated with hyperestrogen states, endometrial polyps
  • Multifocal lesions associated with lobular endocervical glandular hyperplasia / pyloric gland metaplasia (Histopathology 2009;54:184)
  • May produce mucometra if cervical stenosis present
  • Mucin pools are associated with neutrophils

Micro images

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Left: simple mucinous metaplasia in the basalis of an atrophic endometrium
Middle: Complex papillary mucinous metaplasia in curettings
Right: Complex endometrioid hyperplasia with a glandular space lined by micropapillary mucinous metaplasia (arrow)

Papillary proliferation / papillary change
  • Rare, usually postmenopausal women
  • May be similar to papillary syncytial change
  • Usually benign behavior
  • Polypectomy or curettage appears to be adequate treatment (Am J Surg Pathol 2001;25:1347)
  • More aggressive treatment may be needed for extensive complex papillary proliferations

Gross description
  • 0.7 cm to 3.0 cm in size, 2/3 occur in endometrial polyps

Micro description
  • Focal areas of fibrovascular cores without atypia, usually near endometrial surface
  • Either simple or complex papillary patterns
  • Often metaplastic epithelial changes

Micro images

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Papillae are limited to the surface
epithelium and composed of
bland uniform lining cells

Cytology description

Differential diagnosis
  • Well differentiated / low grade papillary adenocarcinoma

Squamous metaplasia
  • Occurs in normal or hyperplastic endometrium, polyps and leiomyomas; also as part of malignant processes
  • Usually diffuse (adenoacanthosis) or in morules (rounded aggregates of bland cells with indistinct cytoplasmic borders)
  • Usually in premenopausal women with exogenous hormones (Arch Pathol Lab Med 1995;119:458) or with polycystic ovary disease; also associated with foreign body reactions, chemical irritants and endometritis
  • Note: central necrosis of morules is common and not specific for malignancy
  • Ichthyosis uteri: complete replacement of endometrium by squamous epithelium; may be associated with malignancy (Diagn Pathol 2006 May 19;1:8)

Micro images

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Squamous metaplasia

Left: with squamous cell carcinoma; right: with endometrioid carcinoma

Squamous and
metaplasia post
tamoxifen therapy

Differential diagnosis

Stromal metaplasia

Micro images

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Endometrial stromal
nodule with smooth
muscle metaplasia

Differential diagnosis
  • Retained fetal parts

Syncytial change
  • Also known as papillary syncytial change, surface syncytial change
  • Finding in endometrial biopsies and curettings from patients with uterine bleeding
  • Associated with anovulatory dysfunctional bleeding, endometrial hyperplasia, estrogen usage or other hormonal treatment
  • Appears to be degenerative, not reparative (Int J Gynecol Pathol 2008;27:534)

Micro description
  • Denuded endometrial surface produced by breakdown or breakthrough bleeding covered by sheet-like plaque of regenerating epithelial cells, often eosinophilic, without discrete cell boundaries (Mod Pathol 2000;13:309)
  • Nuclear debris, neutrophils and rounded clumps of endometrial stromal cells usually present
  • Usually no papillae with fibrovascular cores
  • May resemble microglandular hyperplasia due to small glandular lumina or pseudolumina

Micro images

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Surface papillary syncytial change


Positive stains

Tubal (ciliated cell) metaplasia
  • Markedly increased ciliated cells (nonmetaplastic endometrium have some ciliated cells), resembles fallopian tube; often seen with endometrial hyperplasia and other hyperestrogenic states
  • Presence of atypia does not affect prognosis (Mod Pathol 2011;24:1254)

Micro Images

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Tubal-type ciliated epithelium

Tubal metaplasia

Complex stellate; complex, cribriform glands; mosaic p16 positivity

Positive stains
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