Proliferative activity of cutaneous melanocytic tumors defined by Ki-67 monoclonal antibody. A quantitative immunohistochemical study

Abstract

In various tumors, proliferative activity has been demonstrated to be closely related to the degree of malignancy. In the present study, we examined the proliferative pool in a total of 25 melanocytic (nevocytic) skin tumors by immunohistochemical staining with Ki 67 monoclonal antibody (labeling the G1, S, G2-phase of the cell cycle) and quantitative morphological evaluation. There were highly significant differences in the numerical density of Ki 67-positive cells between nevocellular nevi (number of positive cells: 2.2 +/- 0.7 X 10(3)/mm3), primary malignant melanoma (6.3 +/- 1.9 X 10(3)/mm3), and metastatic malignant melanoma (47.0 +/- 9.2 X 10(3)/mm3). Within the malignant melanoma group, there was a significant correlation between proliferative activity and maximum tumor thickness (r = 0.85; p less than 0.05). Comparison with previous studies using tritiated thymidine labeling and colony-forming efficiency shows that the stereological evaluation of Ki 67 staining in melanocytic skin tumors provides a reliable estimate of proliferative activity, which might be of prognostic value.