Case ReviewsMixed Small Cell Neuroendocrine Carcinoma and Conventional Acinar Adenocarcinoma of the Prostate A Case ReportCordeiro-Rudnisky, Fernanda MD*; Wu, Yubo DO†; Sun, Yue MD†Author Information From the *Department of Pathology, Albany Medical Center, Albany, NY †Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA. Reprints: Yue Sun, MD, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215. E-mail: firstname.lastname@example.org. The authors have no funding or conflicts to declare. AJSP: Reviews & Reports: May/June 2020 - Volume 25 - Issue 3 - p 112-113 doi: 10.1097/PCR.0000000000000382 Buy Metrics Abstract Prostate cancer with neuroendocrine (NE) differentiation can be classified into six categories: conventional adenocarcinoma with NE differentiation, adenocarcinoma with Paneth cell–like NE differentiation, carcinoid tumor, small cell carcinoma, large cell carcinoma, and mixed NE carcinoma-acinar adenocarcinoma. Mixed NE carcinoma-acinar carcinoma is a biphasic carcinoma characterized by the presence of NE (small or large cell) carcinoma and conventional acinar adenocarcinoma. In rare cases, these two components overlap without discrete classic small cell carcinoma or a usual prostate adenocarcinoma component, making it particularly difficult to determine whether these overlapping cases should be diagnosed as small cell carcinoma or adenocarcinoma with a high Gleason score. Here, we present the case of a 74-year-old man who was diagnosed with mixed small cell NE carcinoma and conventional acinar adenocarcinoma of the prostate. © 2020 Lippincott Williams & Wilkins, Inc.