Prostatic intraepithelial neoplasia: its morphological and molecular diagnosis and clinical significance.

The aim of the present paper was to review the morphological spectrum of prostatic intraepithelial neoplasia (PIN), its relationship to carcinoma of the prostate (PCa) and its clinical significance. We reviewed the literature on premalignant lesions of the prostate, with an emphasis on high grade prostatic intraepithelial neoplasia (HGPIN). HGPIN is the most likely precursor of PCa, according to almost all available evidence. HGPIN is characterized by cellular proliferations within pre-existing ducts and acini, with nuclear and nucleolar enlargement similar to PCa. The clinical importance of recognizing HGPIN is based on its association with PCa. In recent years, a significant decline from 36% to 22% in the predictive value of cancer after an initial diagnosis of HGPIN. A major factor contributing to the decreased incidence of cancer after a diagnosis of HGPIN on needle biopsy in the contemporary era is related to increased needle biopsy core sampling, which detects many associated cancers on initial biopsy. Some recent studies have suggested that molecular findings associated with HGPIN might be able to predict which men are more likely to have cancer on re-biopsy.