Quantitative study of KI-67 antibody staining in non-Hodgkin's lymphomas using image analysis

In sections from 32 B malignant lymphomas (ML), the total KI-67 stained area was compared to the number of KI-67 positive cells in order to demonstrate the reliability of using image analysis to quantify the proliferative activity. The total KI-67 area percentage correlated highly with the number of KI-67 positive cellular profiles (r = .93). Significant differences were found between low- and high-grade ML according to the Kiel classification (mean values +/- SD, respectively, of 7.7 +/- 3.81% and 16.6 +/- 6.23%), and between low-, or intermediate- and high-grade ML only, according to the International Working Formulation. Within the Working Formulation, the statistical analysis grouped the diffuse large cell subtype of intermediate grade with the immunoblastic high-grade subtype. A wide range of KI-67 area percentage values was noted, particularly in follicular ML; for these follicular ML, considering follicular areas only, values were comparable to high-grade ML (14.8 +/- 6.60%). In conclusion, the KI-67 area percentage is a reliable alternative method to manual cell counting, and image analysis allows quicker measurements appropriate to large and strictly lymphomatous areas, using a greater number of cells than in manual cell counting.