Endometrial hyperplasia

See Endometrium for dating and benign pathologies.

Endometrial hyperplasia, abbreviated EH, is a precursor to endometrial carcinoma.

Overview

The most widely used system is from the World Health Organization (WHO). The WHO system is based on determining:

1. Gland density (normal = simple hyperplasia, high density = complex hyperplasia), and
2. Presence of atypia.

An alternative grading system from Harvard exists. It is not widely used. It defines a term called endometrial intraepithelial neoplasia (EIN).

WHO system

Management of endometrial hyperplasia

• Endometrial hyperplasia with atypia is usually treated with hysterectomy.
  • In women who want to maintain fertility it may be treated with progestin + short interval re-biopsies (q3 months).
• Endometrial hyperplasia without atypia is treated by:
  • Progestins + close follow-up OR hysterectomy.

Risk of progression to carcinoma

Approximate risk of progression to carcinoma:

	Simple	Complex
Without atypia	1%	3%
With atypia	9%	27%

WHO system

Simple endometrial hyperplasia

General

• More common than simple endometrial hyperplasia with atypia.

Microscopic

Features:

• Irregular dilated glands (with large lumens) - key feature.
  • Glands described as "animal shapes".
• Variation of gland size.
• No nuclear atypia.
  • Uniform columnar nuclei.
• Normal gland density (gland area in plane of section/total area ~= 1/3).

DDx:

• Disordered proliferative phase.

Images:

• Simple endometrial hyperplasia - low mag. (WC).
• Simple endometrial hyperplasia - high mag. (WC).

Simple endometrial hyperplasia with atypia

General

• Uncommon.

Microscopic

Features:

• Irregular dilated glands (with large lumens) - important feature.
  • Glands described as "animal shapes".
• Variation of gland size.
• No nuclear atypia.
  • Uniform columnar nuclei.
• Normal gland density (gland area in plane of section/total area ~= 1/3).
• Nuclear atypia:
  • Loss of basal nuclear stratification.
  • Nuclear size variation.
  • Nuclear rounding.
    • Nuclei lacking atypical = uniform columnar nuclei.
  • Nucleoli.
  • Hyperchromasia or vesicular nuclei.

Notes:

• There are no clear criteria for atypia. Different sources list different features.
• VL criteria for atypia (all should be present):
  1. Increased NC ratio.
     • Atypical: ~ 1:2
     • Not atypical: ~1:3.
  2. Oval nuclei with small major axis to minor axis ratio.
     • Atypical: major axis:minor axis = <=2:1.
     • Not atypical: major axis:minor axis = >=3:1
       • NB: round nuclei: major axis:minor axis = 1:1.
  3. Small nucleoli (~1/5 the size of the nucleus).

Complex endometrial hyperplasia

Microscopic

Features:

• Increase in size & number of glands + irreg. shape.
  • Need cribriform architecture.
  • Two "touching" glands are likely one gland in section.
• Cell stratification.
• Nuclear enlargement.
• Mitoses common.
• No nuclear atypia.

Notes:

• Normal gland-to-stroma ratio is 1:3.

Image:

• Endometrial hyperplasia (webpathology.com).

Endometrial carcinoma vs. complex endometrial hyperplasia:

• Complex endometrial hyperplasia: non-confluent (glands distinct from one another).
• Diagnosis of complex EH is based on histology (cytologic features).

Complex endometrial hyperplasia with atypia

Microscopic

Features:

• Increase in size & number of glands + irreg. shape.
  • Need cribriform architecture.
  • Two "touching" glands are likely one gland in section.
• Cell stratification.
• Nuclear enlargement.
• Mitoses common.
• Nuclear atypia present.

Image:

• Complex endometrial hyperplasia with atypia (webpathology.com).

See also

• Endometrium.
• Endometrial carcinoma.
• Gynecologic pathology.