Prostatic intraepithelial neoplasia and the origins of prostatic carcinoma

The participants agreed that high grade prostatic intraepithelial neoplasia was the most likely precursor of prostate cancer. Consensus was reached regarding grading, suggesting that PIN be classified as low grade and high grade, noting that high grade PIN is the clinically significant end of the morphologic continuum. Grade 1 PIN is now considered low grade, and grades 2 and 3 are considered high grade. All participants agreed that urologists should be informed when high grade PIN is identified in isolation in tissue specimens, but consensus was not reached regarding the value of reporting low grade PIN. No therapy was recommended for patients with high grade PIN, although repeat biopsy and follow-up is of value. No consensus was reached regarding the biologic potential of the lesion known as atypical adenomatous hyperplasia. Further investigation is needed to determine the diagnostic utility of this finding in prostatic specimens.