Association of intraductal carcinoma of the prostate detected by initial histological specimen and neuroendocrine prostate cancer: A report of three cases.

We present three cases of neuroendocrine prostate cancer (NEPC) and histologically investigate the association of intraductal carcinoma of the prostate (IDC-P) and NEPC. Case 1 was a 76-year-old man who had NEPC identified by repeated biopsy specimens when his prostate-specific antigen (PSA) level became elevated 8 years after the initiation of androgen deprivation therapy (ADT). Case 2 was a 70-year-old man who had NEPC detected when multiple bone metastases were found 3 years after the initiation of ADT. Case 3 was a 70-year-old man who was diagnosed with NEPC based on histological examination of transurethral resected specimens. The histological findings in these three cases showed mixed neuroendocrine carcinoma-acinar adenocarcinoma with various proportions of both components. In all three cases, the neuroendocrine carcinoma components were positive for synaptophysin and chromogranin A, whereas the adenocarcinoma components were positive for PSA and NKX3.1. When we retrospectively reviewed the initial hematoxylin and eosin-stained slides, IDC-P was detected in all three cases. Furthermore, we collected nine additional cases of NEPC and found that all six cases with initial biopsy specimens available had an IDC-P component. Detecting IDC-P on initial histological specimens of the prostate may predict transformation to NEPC.