Figure 1
The stepwise counting procedure in tabular form. Start by counting 50 cells in a hot spot. If 0-2 cells are positive, declare the sample as Ki67-negative, and if 19-50 cells are positive, declare as Ki67-positive. If the number of positive cells is in the 3-18 range, count another 10 cells. If the null hypothesis was not rejected in the first step, the number of positive cells out of 60 will vary between 3+0 = 3 and 18+10 = 28. The three possible decisions based on 60, 70, …, 400 cells are listed in the table. The color-coding is green for low Ki67, red for high Ki67 and yellow for equivocal Ki67 status.