SYP and Familial prostate cancer: Prostate cancer with neuroendocrine differentiation is typically defined by the heterogeneous histological expression of several NE markers in at least 5% of epithelial cells, including chromogranin A (CHGA), synaptophysin (SYP), neural cell adhesion molecule 1 (NCAM1), and enolase 2 (ENO2) (9).