prostatic intraepithelial neoplasia (PIN)

Introduction

premalignant lesions of prostate; term encompasses intraductal dysplasia, large acinar atypical hyperplasia, atypical primary hyperplasia, hyperplasia with malignant change, marked atypia and duct-acinar dysplasia.

Microscopic pathology

low grade PIN

• epithelial cell crowding, stratification, irregular spacing
• enlarged nuclei, variable sized, rarely prominant nucleoli
• basal cell layer intact
• basement membrane intact

high grade PIN

• more crowding & stratification of epithelial cells, 4 patterns: tufting, micropapillary, cribriform, flat
• enlarged nuclei, some variability in size & shape, hyperchromatic, chromatin clumping, variably frequent large & prominant nucleoli
• basal cell layer may show some disruption
• basement membrane intact

More general terms

• prostatic neoplasm