Endometrial metaplasia

Uterus

Nontumor

Topic Completed: 1 March 2012

Minor changes: 23 December 2020

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed search::endometrial metaplasia uterus

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

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Table of Contents

Cite this page: Pernick N. Endometrial metaplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusmetaplasia.html. Accessed February 27th, 2021.

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

CK20, CDX2, chromogranin, villin (Int J Gynecol Pathol 2011;30:492)

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

Endometrial glandular and stromal breakdown with papillary metaplasia may resemble well differentiated adenocarcinoma due to similar nuclear size (Diagn Cytopathol 2009;37:487); may have metaplastic clumps with irregular protrusions (Diagn Cytopathol 2006;34:665)

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)

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Squamous metaplasia

With squamous cell carcinoma

Squamous and
mucinous
metaplasia post
tamoxifen therapy

Differential diagnosis

Well differentiated endometrial adenocarcinoma with squamous metaplasia

Stromal metaplasia

Formation of smooth muscle, cartilage and bone
May be it difficult to assess myometrial invasion in carcinoma (Int J Gynecol Pathol 2007;26:115)

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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

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Surface papillary syncytial change

p16+

Positive stains

p16 (INK4A) (J Clin Pathol 2011;64:97)

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 metaplasia

Complex stellate; complex, cribriform glands; mosaic p16 positivity

Positive stains

p16 (Cell Oncol 2007;29:37), MUC5AC (52%, Mod Pathol 2005;18:1243)