• Clinical science

Benign tumors of the endometrium


The most common benign tumors of the endometrium are endometrial hyperplasia and endometrial polyps. Endometrial hyperplasia is caused by an increased estrogen stimulation and manifests with irregular, often heavy vaginal bleeding. There are 2 types of endometrial hyperplasia: endometrial hyperplasia with atypia and endometrial hyperplasia without atypia. Diagnosis involves ultrasound (to assess the thickness of the endometrium) and biopsy (to assess atypia). Treatment of endometrial hyperplasia without atypia consists mainly of progestin therapy, while endometrial hyperplasia with atypia requires hysterectomy. Endometrial polyps are localized overgrowths of endometrial tissue that mainly affect postmenopausal women. Though usually asymptomatic, endometrial polyps can cause irregular vaginal bleeding and, in premenopausal women, infertility. Diagnosis is made with ultrasound or hysteroscopically. Treatment involves watchful waiting in asymptomatic patients and surgical removal in symptomatic patients.

Endometrial hyperplasia

Classification of endometrial hyperplasia based on histology (WHO 2014) [1]
Endometrial hyperplasia without atypia (benign endometrial hyperplasia) Endometrial hyperplasia with atypia (endometrial intraepithelial neoplasm)
  • Both stromal and glandular cells
  • Appearance varies
    • Simple endometrial proliferation with a few cysts
    • Enlarged, dilated mucous membrane glands (Swiss cheese pattern) located between abundant stromal tissue
Risk of carcinoma
  • Low (1–3%)
Treatment of endometrial hyperplasia based on histology
Premenopausal women Postmenopausal women
Endometrial hyperplasia without atypia
Endometrial hyperplasia with atypia
  • In women with completed childbearing or no future wish to conceive: total abdominal hysterectomy with or without bilateral salpingo-oophorectomy
  • In women with a wish to conceive: progestin therapy and close surveillance with regular endometrial sampling
  • Total abdominal hysterectomy with bilateral salpingo-oophorectomy

Endometrial polyps