MKI67 and neoplasm: Tumor microenvironment resulted as different in two ACC subtypes: in ACC-I more epithelial tumour cells and intratumoural natural killer cells were counted, with a higher expression of Ki67 and B7-H4 and in the stroma more immune cells and cytotoxic T cells were observed; in ACC-II there was a higher density of fibroblasts and myoepithelial p63+ tumour cells (90).