Prostate cancer with Paneth cell-like neuroendocrine differentiation and extensive perineural invasion: coincidence or causal relationship?

The case of a 74-year-old man is reported who suffered from a locally advanced prostate cancer treated by neoadjuvant hormonal ablation, followed by prostatectomy. Histological examination of the prostatectomy specimen disclosed an adenocarcinoma with partial, Paneth-like, neuroendocrine differentiation. Extensive perineural tumor invasion was found with a total of 921 perineural tumor foci. Neuroendocrine differentiation of tumor cells was accentuated in perineural locations and was associated with an elevated expression of N-CAM and vimentin, and a reduced expression of E-Cadherin and Ki-67. We hypothesize that neuroendocrine differentiation may promote perineural invasion of prostate cancer cells by a "catherin-switch" and by mechanisms involving epithelial-mesenchymal transition.