MKI67 and Menkes disease: Ki67 immunohistochemistry produced a mean Ki67 proliferative index (PI) of 50.4% ± 1.62 in the WD, 65.2% ± 1.9 in MD and 29.5% ± 1.8 in PD adenocarcinomas (Figure 5C: WD/MD, ***P < 0.001; MD/PD, *P < 0.05; and WD/PD, *P < 0.05).