MKI67 and neuroendocrine carcinoma: Values <3% of Ki67 index and <2/10 HPF (10 mm2) of mitotic count determines NET G1; 3–20% of Ki67 index and 2–20/10 HPF (10 mm2) of mitotic count, reveals NET G2; >20% of Ki67 index and > 20/10 HPF (10 mm2) of mitotic count, according to their morphological differentiation, is classified as NET G3 or NEC G3.3