prostatic intraepithelial neoplasia (PIN)

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

References

Bostwick & Eble. Urologic Surgical Pathology. Mosby 1997.