Utility of Argyrophilic nucleolar organizer regions (AgNOR) in differentiating malignant from benign of colorectal tumors.

Background: Argyrophilic nucleolar organizer regions (AgNOR) can reflect the activity of cellular proliferation. The purpose of this study is to evaluate the potential value of AgNOR in differentiating benign from malignant colon epithelial neoplasms, and to determine the correlation between the nucleus AgNOR and the grade of colonic adenocarcinomas.

Methods: In this study, AgNOR technique was applied to 61 paraffin embedded sections of colorectal tissue including normal mucosa (n = 10), adenomatous polyp (n = 16), and adenocarcinoma (n = 35).

Results: The mean +/- standard error (SE) numbers of AgNOR dots per nucleus of normal mucosa, adenomatous polyp, and adenocarcinoma were 2.17 +/- 0.07 (n = 10) 3.89 +/- 0.10 (n = 16) and 5.52 +/- 0.10 (n = 35), respectively (p < 0.00001). In addition, the mean numbers of AgNOR dots per nucleus of well differentiated (WD) adenocarcinoma (n = 14), moderately differentiated (MD) adenocarcinoma (n = 11) and poorly differentiated (PD) adenocarcinoma (n = 10) were 5.20 +/- 0.12, 5.81 +/- 0.20, 5.67 +/- 0.15, respectively. MD and PD tumor had significantly higher AgNOR count than that of WD tumor (p < 0.05). However, there was no significant difference between MD and PD colorectal adenocarcinoma.

Conclusion: AgNOR method is a simple, rapid method in diagnosis of colorectal tumors, and it provides a useful adjunct to histopathology in the diagnosis of colorectal tumors.