Endometrial Hyperplasia : Differential Diagnosis

Comments:
Endometrial Hyperplasia (EH) - Differential Diagnosis: EH needs to be differentiated from normal proliferative phase endometrium (discussed below), reparative endometrium, endometrial breakdown, various artifacts, disordered proliferative endometrium, cystic atrophy, endometrial polyps, various metaplasias and endocervical reactive proliferations. Within hyperplasias, nonatypical EH should be differentiated from atypical endometrial hyperplasia/endometrioid intraepithelial neoplasia (AEH/EIN). In addition, AEH/EIN should be distinguished from endometrioid and endocervical carcinomas.

Normal Proliferative Phase Endometrium: The glands are spaced out (left panel) with ample stroma in between (gland:stroma ratio <1). Telescoping of glands (right panel) as well as artifactual juxtaposition of glands in a fragmented specimen can create an appearance of glandular overcrowding and mimic AEH/EIN. One should be aware of this artifact and the diagnosis of EH must be made on an intact piece of endometrium.

Isolated clusters of endometrial glands with altered cytology measuring <1 mm may be found in benign endometrium. They usually represent metaplasia or reparative change and should not be mistaken for AEH/EIN.