MKI67 and prostate carcinoma: On standard diagnostic staining, the primary prostate cancer in this case was negative for neuroendocrine markers, but the nodal disease was positive for AR, NKX3.1 (Additional file 1: Fig. S18) and markers of NE differentiation (Synatophysin, and CD56) (Fig. 4A) with a Ki67 index of 60%.