Quantitative estimation of AgNORs in normal, dysplastic and malignant oral mucosa

Aman Chowdhry,Shashwat Mishra,Revati Shailesh Deshmukh,Deepika Bablani,Deepika Shukla

doi:10.5507/bp.2013.002

Abstract

Silver stainable nucleolar organizer regions (AgNORs) have received a great deal of attention recently as their frequency within the nuclei is significantly higher in malignant cells than in normal, reactive or benign neoplastic cells. The objective of this study was to carry out a quantitative assessment of large and small AgNORs in oral normal mucosa, precancerous lesions and infiltrating squamous cell carcinomas. The study comprised 110 formalin-fixed, paraffin-embedded oral mucosal biopsies consisting of 30 oral dysplasia, 60 oral squamous cell carcinomas and 20 normal oral mucosa. AgNORs were counted in each nucleus, categorized as small, large and total number of AgNORs in each cell and their means were calculated. The mean value of small AgNORs, large AgNORs and total AgNORs increased gradually from normal mucosa to dysplastic lesions to squamous cell carcinomas. The study clearly indicates that in oral squamous cell carcinomas, AgNORs diminish in size as they increase in number. Further, AgNOR counts increase as the degree of malignant potential of the cell increases. By combining both the enumeration of AgNORs and their size, good distinction can be made between normal, dysplastic and infiltrating squamous cell carcinomas. This could help in the early diagnosis and prognosis of dysplastic mucosal lesions and their malignant transformation.

Highlights

Millions of new cases of invasive cancer are diagnosed each year of which oral cancer has a considerably high incidence
Nucleolar organizer regions (NORs) are segments of chromosomes encrypted for ribosomal RNA which are present on specific loops of DNA
NORs have received a great deal of attention recently because of the observations that their frequency within the nuclei is significantly higher in malignant cells than in normal, reactive or benign neoplastic cells2,3.they are of diagnostic value for in characterization of the invasiveness in carcinomas[4]

Summary

INTRODUCTION

Millions of new cases of invasive cancer are diagnosed each year of which oral cancer has a considerably high incidence. The endeavor of this study was to carry out a quantitative assessment of large and small AgNORs in specimens of oral normal mucosa, precancerous mucosal lesions and infiltrating squamous cell carcinomas previously diagnosed on H & E stain. The other set of sections was stained for the Argyrophilic Nucleolar Organizer regions by an improved method of Ploton et al 1986 (ref.4) and the AgNOR count was established for each specimen. The total number of AgNORs in each cell was calculated by summing both counts and was initially recorded in a separate table From these values the means of large, small and total AgNORs were obtained and tabulated. Values for P less than 0.05 were regarded as significant

RESULTS

DISCUSSION

CONCLUSION