Small Cell-like Change in Central Zone Histology-A New Observation Mimicking Cribriform Intraductal Prostatic Adenocarcinoma.

A small cell-like change in prostate has been described in high-grade prostatic intraepithelial neoplasia (PIN), intraductal prostatic adenocarcinoma, and invasive prostate cancer. It occurs when these processes have a cribriform architecture. To date, small cell-like change has not been described in benign glands. Herein, I describe such a change in cribriform central zone histology from a radical prostatectomy with a spatially remote treatment naïve Grade Group 3 prostate cancer. The cancer did not have cribriform morphology or intraductal prostatic adenocarcinoma. The small cell-like change was positive for racemase in PIN-4 cocktail and no nuclei were highlighted by Ki-67. This is the first report of a small cell-like change in benign prostate tissue. Although rare, such finding in cribriform architecture of central zone histology can potentially be misinterpreted as a neoplastic process.