The degree of nuclear pleomorphism and mitotic activity is considerably less than those observed in high-grade urothelial carcinomas. Note the regular, round contours of tumor cell nuclei. A few signet ring cells are present; however, they appear empty. Mucin-positive signet ring cells are rarely seen in prostatic adenocarcinoma unlike bladder adenocarcinomas. Occasional cases of high-grade prostate cancer may have significant pleomorphism and such cases can be confidently resolved only with immunohistochemical stains.