What is prostatic intraepithelial neoplasia (PIN) in prostate cancer?

Updated: Jan 14, 2019
  • Author: Lanna Cheuck, DO; Chief Editor: Edward David Kim, MD, FACS  more...
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Prostatic intraepithelial neoplasia (PIN) represents the putative precancerous end of the morphologic continuum of cellular proliferations within prostatic ducts, ductules, and acini.

Two grades of PIN are identified. Low-grade PIN is mild dysplasia. High-grade PIN encompasses moderate and severe dysplasia. High-grade PIN is considered by most to be a precursor of invasive carcinoma. Men with high-grade PIN alone can be started on finasteride and monitored closely.

The continuum that culminates in high-grade PIN and early invasive cancer is characterized by basal cell layer or basement membrane disruption, progressive loss of secretory differentiation markers, increasing nuclear and nucleolar abnormalities, increasing proliferative potential, and increasing variation in deoxyribonucleic acid (DNA) content (aneuploidy).

Clinical studies suggest that PIN predates a carcinoma by 10 or more years. [21] The clinical importance of recognizing PIN is based on its strong association with carcinoma. Studies claim that men with high-grade PIN in a prostate biopsy specimen have a 35-50% chance of being diagnosed with prostate cancer after a subsequent biopsy. [22] Atypical small acinar proliferation (ASAP) has also been associated with higher cancer detection rates.

The identification of PIN in prostate biopsy specimens warrants further searching for concurrent invasive carcinoma. In most men, this means repeat biopsies if the PSA level changes significantly. The same may also be true for ASAP findings after biopsy.

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