MKI67 and neoplasm: Grade 1 denotes a well-differentiated tumor, with a Ki-67 labeling index <3% and a mitotic index <2 per 10 high-power fields (10HPF); grade 2 denotes a moderately differentiated tumor, with a Ki-67 labeling index of 3–20% or a mitotic index of 2–20 per 10HPF [1].