Uterus
Nontumor
Endometrial metaplasia
Author: Nat Pernick, M.D.
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
Table of Contents
Definition / general | Clear cell metaplasia | Eosinophilic (oxyphilic) metaplasia | Intestinal metaplasia | Mucinous metaplasia | Papillary proliferation / papillary change | Squamous metaplasia | Stromal metaplasia | Syncytial change | Tubal (ciliated cell) metaplasiaCite this page: Pernick N. Endometrial metaplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusmetaplasia.html. Accessed January 16th, 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
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)
Micro images
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Squamous metaplasia
With squamous cell carcinoma
Squamous and
mucinous
metaplasia post
tamoxifen therapy
Differential diagnosis
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)
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
p16+
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 metaplasia
Complex stellate; complex, cribriform glands; mosaic p16 positivity
Positive stains
