Nonatypical vs Atypical Endometrial Hyperplasia

Comments:
Endometrial Hyperplasia (EH) - Differential Diagnosis: Nonatypical EH should be differentiated from atypical endometrial hyperplasia/endometrial intraepithelial neoplasia (AEH/EIN).

In AEH/EIN, the cytologic changes (atypia) are focal or multifocal and clearly stand out (left panel, top) in contrast to the background endometrium (left panel bottom). In nonatypical EH, the cytologic and architectural features are diffusely uniform (right panel) throughout the specimen.

Loss of PTEN (44% of cases), PAX2 (71% of cases), or mismatch repair proteins by immunohistochemistry is seen in AEH/EIN. However, routine use in diagnosing AEH/EIN is not recommended as many cases of inactive benign endometrium or nonatypical hyperplasia may also be negative for these markers.