Ultrastructure of prostatic intraepithelial neoplasia.

ABSTRACT

BACKGROUND: Prostatic intraepithelial neoplasia (PIN) is the most likely precursor of prostatic adenocarcinoma. However, the ultrastructural features of PIN have not been defined in properly fixed tissues. METHODS: In this study, we examined a total of 84 acini from 11 cases of high-grade PIN and matched benign epithelium and adenocarcinoma from patients undergoing radical prostatectomy. Specimens from each case were immediately fixed in glutaraldehyde after surgical removal and processed routinely to ensure optimal preservation. RESULTS: High-grade PIN displayed ultrastructural features that were intermediate between those of benign epithelium and adenocarcinoma. These included the presence of cells with a variable number of cytoplasmic secretory vacuoles, luminal apocrine blebs, large nuclei with coarsely clumped chromatin, enlarged nucleoli, prominent apical microvilli, intact or discontinuous basal cell layer, and intact basement membrane. CONCLUSIONS: Our results indicate that PIN shares many ultrastructural characteristics with adenocarcinoma, supporting its role as a premalignant lesion.