Significance of Silver Binding Nucleolar Organizer Regions in Oral Squamous Cell Carcinomas

Background: Cell proliferation is an important factor in the prognosis of malignant neoplasia. The number of argyrophilic nucleolar organizer regions (AgNORs) per cell has been considered as an indicator of the cellular proliferative activity. A study is carried out to examine whether AgNOR numbers relate to the growth rate in squamous cell carcinoma (SCC) of the oral cavity. Aim: To verify the relationship between total AgNORs mean value (mAgNOR) and/or the percentage of cells exhibiting five or more AgNOR dots/nucleus/100 cells AgNORs (proliferative index [pAgNOR]) with histopathologic grading of oral SCC according to Broder’s grading. Materials and Methods: This was a prospective study done over a period of 3 years from May 2012 to June 2015. A total of 50 cases of oral SCC were graded into three groups according to Broder’s grading, namely well-differentiated, moderately differentiated, and poorly differentiated. For NOR study, 3-5 μm-thick sections were stained with 50% aqueous silver nitrate solution. The predominant microscopic pattern of NORs was determined. Quantitative and qualitative analyses of NORs were obtained of all cells present on each histological field. AgNORs were stained by a one-step silver method and examined in representative paraffin sections from 50 cases of oral SCC. Results: The mAgNORs per nucleus was 3.3057 ± 0.11 for the well-differentiated group, 5.324 ± 0.43 for the moderately differentiated, and 8.167 ± 0.22 for the poorly differentiated. The proliferative index in well-differentiated pAgNOR count is 25%, in moderately differentiated count it is 49.7%, and in poorly differentiated count it is 65.4%. Conclusions: AgNOR staining technique seems to be a useful diagnostic tool since differences in AgNOR numeric values can be identified in the different types of oral SCC. This technique is easy to handle and inexpensive, thus justifying its large use in histopathology.