Nucleolar organiser region associated proteins in cutaneous melanotic lesions: a quantitative study.

Using a silver staining technique, nucleolar organiser regions were identified in routinely processed paraffin sections of a range of dermal melanotic lesions. The technique shows argyrophilic NOR associated proteins (AgNORs), which are seen in nuclei as black dots. Although the nuclei of melanocarcinoma in situ, melanocarcinoma per se, and lentigo maligna contained similar numbers of AgNORs, in melanocarcinomas a mean of 7.9 AgNORs per nucleus was found, while in naevocellular naevi, this figure was 1.2. The AgNOR method, which is unknown to most histopathologists, could perhaps be used quantitatively or semiquantitatively to assist in the diagnosis of melanotic lesions in the skin (and elsewhere).