MKI67 and neuroendocrine carcinoma: According to the 2010 World Health Organization (WHO) classification, NETs are classified as NET Grade 1 (mitotic count of <2 per 10 high power field [HPF] and/or ≤2% Ki-67 index), NET Grade 2 (mitotic count 2–20 per 10 HPF and/or 3%–20% Ki-67 index), NET Grade 3 (neuroendocrine carcinoma [NEC] includes small-cell carcinoma and large-cell carcinoma, mitotic count of >20 per 10 HPF and/or >20% Ki-67 index), and mixed adenoneuroendocrine carcinoma [6].