Argyrophilic nucleolar organizer regions in atypical adenomatous hyperplasias, prostatic intraepithelial neoplasias and prostatic neoplasms.

Sections from 104 cases of benign, preneoplastic and neoplastic lesions of the prostate were studied for argyrophilic nucleolar organizer regions (AgNORs). The mean NOR counts in normal controls (2.87) and benign prostatic hyperplasia with or without chronic prostatitis (4.90 and 3.84 NORs/nucleus, respectively) were found to be significantly less (p < 0.001) than that in prostatic intraepithelial neoplasia (PIN) and adenocarcinoma of the prostate (5.65 and 5.78 NORs/nucleus, respectively). The mean AgNOR count of a section with atypical adenomatous hyperplasia was significantly lower than that in PIN. No statistically significant difference was observed between AgNOR counts of high-grade PIN and well-differentiated adenocarcinoma (WDAC; 5.67 vs. 5.78 NORs/nucleus, respectively), however the difference between low-grade PIN and WDAC was statistically significant (5.46 vs. 5.78 NORs/nucleus, p < 0.005). The increase in NOR counts occurred concomitantly with the decrease in the degree of differentiation of adenocarcinoma. Thus, NOR was found to be a good adjuvant to the existing diagnostic parameters to pick up more cases at the stage of PIN when prognosis is better.