NeuroD1 is inactive in baseline prostate cell lines and BPHs, whereas it is actively expressed in cAMP-treated EPN, PC3, and DU145 cells. In our surgical series, positive chromogranin-A, synaptophysin, CD56, and NeuroD1 staining was detected in 26.5%, 4.3%, 3.1%, and 35.5%, respectively (difference between chromogranin-A and NeuroD1: p<0.05). The multivariate analysis showed a strong association between chromogranin-A and microscopic perineural invasion (OR: 2.49; 95%CI, 0.85-7.32; p=0