For Physicians. By Physicians.™

Endometrial Hyperplasia – Current Nomenclature and Treatment

Endometrial intraepithelial neoplasia (EIN) is the precursor of type I endometrioid adenocarcinoma.


There are three categories in the EIN classification:

  • Benign endometrial hyperplasia (benign), a diffuse condition due to prolonged estrogen effect
    • Treatment is hormonal therapy
  • Endometrial intraepithelial neoplasia (premalignant), a focal abnormality progressing to diffuse, precancerous in nature
    • Treatment can be hormonal therapy or surgery
  • Endometrial adenocarcinoma, endometrioid type, well differentiated (malignant), a focal abnormalitiy progressing to diffuse
    • Treatment is surgical.

Criteria for diagnosing endometrial intraepithelial neoplasia include the following:

  • Architectural change with area of glands greater than stroma
  • Cytologic abnormality in area of architectural change
  • Size of abnormal area > 1 mm
  • Not a polyp, area of repair, secretory endometrium (excludes mimics)
  • Not carcinoma (excludes cancer)


Endometrial hyperplasia can be a precursor to adenocarcinoma of the endometrium. Distinguishing between hyperplasia and a precancerous lesion is important in optimizing management. The endometrial intraepithelial neoplasia (EIN) classification described here is intended to achieve this, while incorporating pathologic criteria that have become available since the World Health Organization’s 1994 four-class classification was developed.


  • The EIN system appears to increase reproducibility and reduce subjective, descriptive interpretation of pathology
  • Hysteroscopy with directed biopsy of any discrete lesions is the best way to confirm a premalignant endometrial lesion and to exclude endometrial carcinoma
  • Both suction curettage and dilation and curettage have significant sampling limitations
  • Acceptable surgical treatment is hysterectomy, abdominal, vaginal or minimally invasive, with or without removal of fallopian tubes and ovaries
    • Supracervical hysterectomy and morcellation are contraindicated
  • Medical treatment, progestins, can be offered to patients who wish to retain fertility, desire uterine retention, or have multiple medical comorbidities
    • Medroxyprogesterone acetate and megestrol acetate are most commonly used
    • The 52 mg levonorgestrel containing IUD provides another option
    • Regression rates approach 90% with any of the above

Learn More – Primary Sources

ACOG Committee Opinion No. 631: Endometrial intraepithelial neoplasia

Oral progestogens vs levonorgestrel-releasing intrauterine system for endometrial hyperplasia: a systemic review and meta-analysis

Levonorgestrel-releasing intrauterine system vs oral progestins for non-atypical endometrial hyperplasia: a systematic review and metaanalysis of randomized trials