Image Description
The differential diagnosis of prostatic ductal adenocarcinoma includes high-grade PIN, colonic adenocarcinoma infiltrating into the prostate, and papillary urothelial carcinoma. With high molecular weight cytokeratin immunostain, prostatic ductal adenocarcinoma shows complete lack of basal cells (as seen in this image). High-grade PIN would show at least a few residual basal cells in such an extensive focus.