High-grade prostatic intraepithelial neoplasia of the prostate: the precursor lesion of prostate cancer.

High-grade intraepithelial neoplasia (HGPIN) is a lesion which is widely believed to be a precursor of prostatic adenocarcinoma. Correct morphologic identification of HGPIN and an understanding of how this diagnosis affects clinical management in the research setting are necessary as HGPIN is a premalignant lesion with many genetic alterations similar to prostate cancer, but is not yet invasive cancer. As such it is critical to differentiate between benign entities, HGPIN, and prostatic adenocarcinoma for experimental design and data interpretation. This review discusses HGPIN, clarifies the terminology used in pathology reports, and describes the clinical and research implications of this entity.