Nucleolar organizer regions in squamous cell carcinoma of the head and neck

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Abstract
Nucleolar organizer regions are collections of nucleolar proteins associated with ribosomal genes that can be visualized in histologic sections using a silver colloid stain, thus the term silver-staining nucleolar organizer region (AgNOR). In some tissues, the number of AgNORs per nucleus correlates with cellular proliferation and, independently, with malignant change. AgNORs were studied in 66 paraffin-embedded head and neck squamous cell carcinomas and in 12 samples of normal tonsillar squamous epithelium. Carcinomas had a significantly higher mean AgNOR count than the benign epithelium (P <.0001). Among carcinomas, mean AgNOR count increased with stage of the disease (P <.001), but there was no significant correlation with histologic grade or DNA ploidy as determined by flow cytometry. These data suggest that AgNOR count should be evaluated as a possible aid in differentiating benign from malignant squamous epithelial proliferations in the head and neck, and also possibly as a prognostic marker in these carcinomas.