Vascular architecture of melanocytic skin tumors. A quantitative immunohistochemical study using automated image analysis.

The present study examines the distribution of blood vessels in melanocytic skin tumors. Fresh frozen sections of 11 cases each of benign nevocellular nevus, primary malignant melanoma and metastatic malignant melanoma were stained with the endothelium-specific monoclonal antibody BMA 120 and evaluated by an automated image analysis system. Additionally, the proliferative activity was assessed in parallel sections using Ki 67 monoclonal antibody. There were only slight differences between the diagnostic groups as to the vascular distribution in the tumor center, but there were remarkable differences in the connective tissue at the base of the lesions: The area occupied by small vessels (minimum diameter less than 20 microns) was 0.3 +/- 0.05% in benign nevi, 0.6 +/- 0.05% in primary malignant melanoma, and 1.2 +/- 0.10% in metastatic malignant melanoma (U-test: p less than or equal to 0.05). The proliferative activity within each lesion showed a strong positive correlation with the number of small vessels at the base of the tumor (linear regression analysis: r = 0.86; p less than or equal to 0.0001). The findings demonstrate that neovascularization in malignant melanocytic tumors takes place predominantly in the surrounding host tissue and is closely related to the proliferative activity.