The assessment of AgNORs in grading of head and neck non-Hodgkin's lymphoma

Nucleolar organizing regions (NORs) are loops of rDNA, which in humans, occur on the short arms of five acrocentric chromosomes, namely, 13, 14, 15, 21, and 22. NORs are usually demonstrated by binding their associated proteins (NORAPs) to silver (Ag+) ions. The reaction is called AgNORs. It has been determined that the number and the size of NORs are related to the proliferative activity and grade of malignancy.The purpose of this study was to determine the value of AgNOR method in assessment of the grade of malignancy in non-Hodgkin’s lymphoma (NHL) of the head and neck. Forty-one cases of paraffin embedded specimens of NHL, classified by the working formulation system, were selected and then examined by the AgNOR method. AgNORs were enumerated for all 41 cases of NHL (Standard Crocker). The mean AgNORs in 11 cases of low-grade, 15 cases of intermediate-grade and 15 cases of high-grade NHL was 1.66 (SEM = 0.098), 2.52 (SEM = 0.084), and 5.19 (SEM = 0.11), respectively. Through the analysis of variance and multiple comparison, a significant difference was found between the three groups of NHL (P < 0.0001). AgNORs is a reliable method, which could be used in grading of NHL in the head and neck area.