MKI67 and neuroendocrine carcinoma: Ki-67 labeling index and the mitotic count are used for classification into categories from G1 to G3.[15] Poorly differentiated NEC classified as G3 NEC, either the large- or small-cell 1, which both with a high mitotic rate >20 per 10 high-power fields and Ki-67 labeling index of >20%.[15]