Neuroendocrine Tumors of the Prostate and Molecular Features

Prostate cancer is the third most common carcinoma among men. The World Health Organization (WHO) currently divides neuroendocrine (NE) tumors into conventional prostatic adenocarcinoma, carcinoid tumor (WHO’s well-differentiated neuroendocrine tumor), small cell carcinoma (WHO’s poorly differentiated neuroendocrine carcinoma), and paraganglioma. Recently, a new morphologic classification of prostate cancer with neuroendocrine differentiation is proposed that includes usual prostate adenocarcinoma with NE differentiation, adenocarcinoma with Paneth cell NE differentiation, carcinoid tumor, small cell carcinoma, large-cell NE carcinoma (LCNEC), and mixed (small or large-cell) NE carcinoma–acinar adenocarcinoma. Specific criteria have been described to diagnose each entity which should help in standardizing diagnostic terminology in order to be clinically more relevant. Tumors like carcinoid tumor, paragangliomas, and LCNEC are very rare in the prostate. Majority of the tumors with NE differentiation in the prostate are the usual prostate adenocarcinoma with NE differentiation, small cell carcinoma, and mixed small cell–acinar adenocarcinoma. Many of these entities especially small cell carcinoma and LCNEC emerge after androgen deprivation therapy for the usual prostate adenocarcinoma.