Relationship between atypical adenomatous hyperplasia (AAH), prostatic intraepithelial neoplasia (PIN) and prostatic adenocarcinoma.

Two histopathologic lesions are considered putative precursors of prostate cancer, but the supportive evidence for one (prostatic intraepithelial neoplasia, or PIN) is much greater than the other (atypical adenomatous hyperplasia, or AAH). High grade PIN is the most likely precursor of carcinoma, arising in the peripheral zone, but probably does not account for well-differentiated cancer arising in the transition zone. The biological significance of atypical adenomatous hyperplasia of the prostate (AAH) is inconclusive at the time. The histological and cytological features of AAH are intermediate between BPH and low grade carcinoma, suggesting that AAH may be a precursor of well differentiated transition; zone carcinoma. In the recent time new findings on morphogenetic aspects of normal and abnormal prostatic growth i.e. stem cell models are discussed and topics about grading and proliferative activities, frequency and histological changes associated with aging as well as clinical relevance of PIN and AAH. This paper reviews the results and discussion at the second international consultation meeting on PIN in Mayo Clinic, Rochester, Nov. 3-4 th. 1995, following the first international consultation meeting of AAH and PIN and origin of the prostatic carcinoma in Ancona, Sept. 11-12 th 1994.