Preneoplastic lesions of the prostate-clinical, pathological and molecular biological aspects

Needle biopsy is the mainstay of definitive diagnosis of prostate cancer (PCA). While prostate-specific antigen (PSA) screening has facilitated early diagnosis of PCA, it has also resulted in an increase in the proportion of prostate biopsies showing various preneoplastic lesions (PNLs). At times such lesions are the sole finding in the limited amount of tissue available for assessment in an individual biopsy. Hence accurate identification of these lesions is important to avoid errors in the diagnosis of prostatic malignancy and in patient management. Furthermore, some interesting observations have been made regarding the molecular biological aspects of various PNLs during the last decade. In parallel with anatomic and physiological differences in various human races, racial differences have also been observed regarding the incidence of prostatic intra-epithelial neoplasia. This review focuses on prostatic intraepithelial neoplasia (PIN), atypical adenomatous hyperplasia (AAH) and atypical prostatic glands or atypical small acinar proliferation (ASAP) as putative preneoplastic lesions of the prostate. These lesions are reviewed with reference to their overall incidence, histopathological findings, histological differential diagnosis, clinical significance and molecular biological aspects.