Argyrophilic nucleolar organizer regions in the evaluation of tumour progression in the oral mucosa : correlation with tissue pathology

The present study has analysed the numbers of argyrophilic nucleolar organizer regions (AgNOR) in normal tissues and in premalignant and malignant lesions of the oral mucosa in order to assess their potential as a biological marker for tumour progression. On comparison of AgNOR numbers in different lesions, carcinomas showed the highest number (4.65 +/- 0.98) compared to leukoplakias (2.38 +/- 0.47) and normal tissues (1.53 +/- 0.39). Spindle cell carcinomas and poorly differentiated squamous cell carcinomas had higher AgNOR counts than well-differentiated carcinomas. In various clinically different types of oral leukoplakia, the lowest AgNOR counts were observed in homogenous leukoplakia and the highest in speckled leukoplakia. No significant difference in AgNOR number was observed between non-dysplastic and dysplastic leukoplakia, although a significant difference was evident between dysplastic leukoplakia and normal oral mucosa. Correlating the AgNOR count and tumour progression, a significantly high positive correlation coefficient (r = 0.7969, P = 0.0000) was observed.