MKI67 and neoplasm: Furthermore, the WHO 2010 grading classification just used the terminology “high-grade” and “poorly-differentiated” interchangeably for neoplasms in the G3 category, while recent studies have further focused on the heterogeneity of “G3 p-NECs”, in which some might primarily present a high Ki-67 proliferative rate but be morphologically well-differentiated [23].