Is high-grade prostatic intraepithelial neoplasia (HGPIN) a reliable precursor for prostate carcinoma? Implications for clonal evolution and early detection strategies.

High-grade prostatic intraepithelial neoplasia (HGPIN) is a documented putative precursor lesion for invasive prostate adenocarcinoma. However, the precise mechanisms of the carcinoma's development from HGPIN are unclear. Many studies have attempted a comparative molecular genetic characterisation of HGPIN and its corresponding carcinoma to study this transformation. However, to date, some HGPIN mimickers, such as intraductal carcinoma, which can engage in retrograde colonisation of the prostatic acini in an HGPIN-like manner, have been described. In this work, we hypothesise that the lesion formerly known as HGPIN adjacent to invasive carcinoma does not necessarily represent its respective precursor lesion. This hypothesis stems from recent morphological, experimental, and theoretical evidence on the development of tumour clonality, as well as recent studies outlining the three-dimensional architecture of prostate adenocarcinomas (most importantly, their interconnection with the tumoural glandular system). Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.