[The nucleolus organizer region in benign and malignant melanocyte lesions of the skin: a quantitative study]

By means of a silver staining method, Nucleolar Organizer Region-associated proteins (NORs) have been evaluated on paraffin sections of two series of benign and malignant melanocytic skin lesions (represented by 30 intradermal naevi and 30 malignant melanomas). A significant difference (P less than 0.001) was found between the numbers of Ag-NORs in the nuclei of benign lesions and those of malignant lesions. It is suggested that this method could be of value in assessing the biological potential of cutaneous melanocytic neoplasms.