MKI67 and neuroendocrine carcinoma: Neuroendocrine carcinoma (NEC) is an aggressive type of neuroendocrine neoplasms (NENs) that was pathologically categorized into three subtypes according to the WHO 2010 classification, and defined by the presence of >20 mitoses per 10 HPF and/or >20% Ki-67 labeling index [1].