Table 1: ENETS/WHO 2010 Classification Guidelines for Gastrointestinal Neuroendocrine Tumors [5].

Grade

Ki-67 index

Mitotic Count

Differentiation

1

≤2%

< 2 per 10 HPF

Well differentiated

2

3-20 %

2-20 per 10 HPF

Well differentiated

3

> 20%

> 20 per 10 HPF

Poorly differentiated