MKI67 and neuroendocrine neoplasm: In particular, well-differentiated neuroendocrine tumors (NETs) show an organoid morphology with bland cytology, and proliferation index stratifies tumors into G1 (mitotic index <2 mitoses/10 high-power fields and/or Ki67 <3%), G2 (mitotic index between 2 and 20 mitoses/10 high-power fields and/or Ki67 between 3 and 20%), and G3 (mitotic index >20 mitoses/10 high-power fields and/or KI67 >20%).