Nuclear volume estimates in prostatic intraepithelial neoplasia

OBJECTIVE: Prostatic intraepithelial neoplasia (PIN), the most likely precu rsor of prostatic adenocarcinoma, is divided into two grades, low and high. Pathologists may encounter difficulties in applying these criteria in dail y practice. In view of the clinical significance of high grade PIN as stron g predictor of carcinoma, the separation of low and high grade PIN plays an important role in patient management. The aim of the present study was to evaluate three-dimensional nuclear size estimation in normal prostatic glan ds, low and high grade PIN, and prostatic adenocarcinoma as an element in t heir classification. STUDY DESIGN: We studied 31 formalin;fixed, paraffin-embedded, whole-mounte d radical prostastectomy specimens that contained foci of normal prostatic glands, low and high grade PIN, and prostatic adenocarcinoma. Hematoxylin-e osin-stained sections were selected for the stereologic estimation of volum e-weighted mean nuclear volume by the "point-sampled intercepts" method. On each focus, an average of six fields of vision were systematically chosen. RESULTS: The quantitative results indicate a significant increase in nuclea r volume from normal prostatic glands (mean, 209.0 mu m(3); SD, 64.6 mu m(3 )) to low grade PIN, high grade PIN and prostatic adenocarcinoma with incre ments of 49%, 88% and 109%, respectively (F=29.1, P<.001). Two-group compar isons (Duncan procedure) showed differences between low and high grade PIN and prostatic adenocarcinoma (P<.01). The difference between high grade PIN and Prostatic adenocarcinoma was not significant. CONCLUSION: Three-dimensional estimates of nuclear sire discriminate low an d high grade PIN. Lack of stereologic differences between high grade PIN an d prostatic adenocarcinoma further supports high grade PIN as a precursor o f prostatic adenocarcinoma.