Abstract: Silver-binding nucleolar organizer regions(Ag-NORs)have been counted in section of routinely processed paraffinembedded tissue blocks.We have examined 55 benign and malignant lesions of larynx by this method.The Ag-NOR counts were 3.29±0.63(n=32)for carcinomas,2.11±0. 34(n=8)for atypical hyperplasia and 1.72 ±0.17(n=14)for papilloma.Carcinomas had significantly higher counts than the other two groups(P<0.01).Between atypical hyperplasia and papilloma groups,the difference of mean Ag-NOR numbers were significant(P<0.01).It may be that the numbers of Ag-NOR reflect cell biological activity or even neoplasia. This method could perhaps be used quantitatively or semiquantitatively to assist in the diagnosis of malignant and benign lesions of larynx or even precancerosis.

Key words: squamous cell carcinoma of larynx, nucleolar organizer regions, pathology