endometrial hyperplasia

Definition: Endometrial hyperplasia is defined as endometrial proliferation with an increase in gland to stroma ratio (from 2:1 to 3:1). It is divided into simple hyperplasia (with or without atypia) and complex hyperplasia (with or without atypia) according to the WHO Classification.

Endometrial hyperplasia is an example of abnormal hormone-induced hyperplasia. After a normal menstrual period, there is a rapid burst of proliferative activity that is stimulated by pituitary hormones and ovarian estrogen.

In regards to endometrial hyperplasia - simple hyperplasia is non-branching, complex is branching. Atypia refers to the cellular characteristics.

Images

 http://www.webpathology.com/image.asp?case=568&n;=1

Parameters

 simple / complex

• If the hyperplastic glands are not branching, the lesion is "simple".
• If the hyperplastic glands are branching, the lesion is "complex".
• Complexity carries a low risk of development of adenocarcinoma.

 No atypia / Atypia

• Simple hyperplasia with atypia has an increased risk of adenocarcinoma.

Types

 simple endometrial hyperplasia

• simple endometrial hyperplasia without atypia
  • http://www.webpathology.com/image.asp?case=568&n;=1
  • http://www.webpathology.com/image.asp?n=2&Case;=568

• simple endometrial hyperplasia with atypia

 complex endometrial hyperplasia

• complex endometrial hyperplasia without atypia
  • In complex hyperplasia, the glands are irregular in size and shape with branching and outpouchings. Cytologic atypia is absent. About 3% of such cases progress to adenocarcinoma.
  • http://www.webpathology.com/image.asp?n=3&Case;=568
  • http://www.webpathology.com/image.asp?n=4&Case;=568
  • http://www.webpathology.com/image.asp?n=5&Case;=568

• complex endometrial hyperplasia with atypia
  • http://www.webpathology.com/image.asp?n=6&Case;=568
  • http://www.webpathology.com/image.asp?n=7&Case;=568
  • http://www.webpathology.com/image.asp?n=8&Case;=568
  • http://www.webpathology.com/image.asp?n=9&Case;=568

Types

 simple endometrial hyperplasia without atypia
 simple endometrial hyperplasia with atypia
 complex endometrial hyperplasia without atypia

• There is no evidence of invasion.
• The basement membrane is intact around the glands and there is no desmoplastic response.
• There is an overgrowth of endometrial glands, making this hyperplasia.
• The glands are branching so the lesion is complex.
• If they were non-branching, it would be classified as simple hyperplasia.
• The cells are not dysplastic / atypical : complex hyperplasia without atypia.
• It carries an increased risk of developing adenocarcinoma.

 complex endometrial hyperplasia with atypia

Differential Diagnosis

 artifacts / compression artifact
 endomatrial cystic atrophy
 endometrial polyp
 endometritis
  metaplasia of the endometrium
 normal endometrium
 disordered proliferative endometrium
-endometrial stromal / glandular breakdown
 metaplastic changes / metaplasia

• squamous and morular metaplasia
• surface syncytial and eosinophilic metaplasia

 uterine endometrioid adenocarcinoma FIGO grade 1

• Degree of atypia between the two is usually similar
• AH / EIN should NOT have:
  • Cribriforming, confluent glands
  • Labyrinthine intraluminal connections
  • Areas of purely solid epithelium
  • Stromal alteration suggesting invasion - desmoplasia (myofibroblasts, edema, inflammation) or necrosis (intervening endometrial stroma replaced by pools of neutrophilic debris)

See also

 endometrial biopsy
 endometrial anomalies
 glandular hyperplasia