The histological diagnosis of endometrial hyperplasia - Is there a need tosimplify?

The intra- and interobserver variability of the histological diagnosis of e ndometrial hyperplasia, including low-grade carcinomas, is high and thus of ten causes confusion in the dialogue between pathologists and clinicians. T he current classification of the WHO, ISGP, and FIGO is not altogether succ essful in overcoming this difficulty. New approaches to resolve this unsati sfactory situation have been suggested by two recent simultaneous studies, one by a European group of experts (1999) and the other by Mutter and The E ndometrial Collaborative Group (2000). Both studies suggest simplifying the WHO classification by reducing the present four categories to two. The Eur opean study names the new histological groups endometrial hyperplasia (EH) and endometrioid neoplasia (EN), while Mutter et al. call them endometrial hyperplasia (EH) and endometrial intraepithelial neoplasia (EIN). Different iation between the two new categories can be made based on uncomplicated mo rphological concepts and confirmed morphometrically by the semiquantitative determination of the stromal volume in relation to total tissue volume (st roma+epithelium+gland lumen). This simplification has the advantage of a hi gh degree of reproducibility of histological diagnoses while facilitating u nderstanding by clinicians. Most importantly, there is no decrease in progn ostic accuracy, since EH is a benign lesion, easily treated with hormones a nd almost without risk of progressing to cancer, while EIN/EN is a pre- or already malignant disease with a high risk of progression (approximate to 3 0%) requiring a more radical treatment. This article summarizes the current discussion on this issue.