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Non tumor

Simple endometrial hyperplasia

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 25 March 2013, last major update February 2012
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.


● Also known as cystic hyperplasia or mild hyperplasia
● Usually evolves to cystic atrophy, 1% to endometrial carcinoma
● Usually lacks cytologic atypia
● Incidence: 142 per 100,000 woman-years, peaks in early 50s (Am J Obstet Gynecol 2009;200:678)
● Relatively low rate of diagnostic agreement between pathologists (Am J Surg Pathol 2008;32:691)


● Progestins, levonorgestrel-releasing intrauterine system (Menopause 2008;15:1002)

Gross description

● Increased endometrial volume, qualitatively different from normal cycling endometrium

Gross images

Endometrial hyperplasia has lush fronds of hyperplastic endometrium

Micro description

● Changes in glands and stroma so that glands are not particularly crowded
● Glands usually round, but may be irregular with cystic dilation
● Lining epithelium is pseudostratified or mildly stratified
● Occasional mitotic figures (less than proliferative endometrium)
● Cellular stroma with variable mitotic activity, uniformly distributed blood vessels

Micro images

Simple hyperplasia
Simple endometrial hyperplasia without atypia
Strong PTEN staining

Figure 1

Figure 2
Figure 3a

Figure 3b

Fig 1:The endometrial glands are irregularly distributed but widely separated by stroma, which is also hyperplastic. The glands are mostly round or tubular, with only a few irregular angularities encountered
Fig 2: Irregularly distributed proliferative-type glands widely separated by active cellular stroma with numerous small, regularly distributed blood vessels
Fig 3a&b: Small and large glands are lined by proliferative-type endometrial epithelium and are widely separated by cellular endometrial stroma

Figure 4

Figure 5

Figure 6

Figure 7

Fig 4: Three cystic glands lined by proliferative~type endometrial epithelium without atypia and separated by cellular stroma
Fig 5: Pre- (left) and post-progestin therapy (middle/right)
Fig 6: Partial response to progestin therapy - compared to pre-treatment, these glands are slightly smaller, less crowded, and are lined by a single layer of cells rather than the proliferative-type epithelium seen above (figure 60). This pattern may be characterized as regressed hyperplasia
Fig 7: Complete response to progestin therapy - another field of the above specimen shows inactive glands in a decidualized stroma. This pattern is characteristic of the response to progestational agents, but the preexisting condition (simple hyperplasia in this case) can no longer be specified by an examination of this material

Cytology description

● May be diagnosed as proliferative endometrium by endometrial brush cytology (Am J Clin Pathol 2000;114:412)

Positive stains

● PTEN (usually, J Med Assoc Thai 2008;91:1161)

Differential diagnosis

Artifacts: fragmented endometrium with artifactually compressed glands
Chronic endometritis: may have reactive glandular changes causing crowding, abnormal gland shapes and variable atypia; but has plasma cells, stromal spindling and edema and surface neutrophils
Cystic atrophy: glands lined by reduced epithelium, stroma is dense and atrophic
Disordered proliferative endometrium: few widely scattered cystic glands, less than hyperplasia
Endometrial polyp: fibrotic stroma with dilated, thick-walled blood vessels

Additional references

Mod Pathol 2000;13:309

End of Uterus > Non tumor > Simple endometrial hyperplasia

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