Introduction:
Mucoepidermoid carcinoma is the most common salivary gland malignancies, classified into three categories as low, intermediate and high.
Because of its highly variable biologic potential, identification of patient's status histologically and proper classification is of high importance in treatment and finally prognosis.
Materials and Methods:
20 samples with the diagnosis of MEC were selected from the archive of the oromaxillofacial pathology department of Mashhad dental school and Ghaem and Omid hospitals which included five samples of grade I, seven samples of grade II and 8 samples of grade III mucoepidermoid carcinoma.
Three sections were taken from each specimen. The first section was stained with H & E, the second one by AgNOR technique and the last one with Ki-67 immunohistochemically.
In each sample, the number of AgNOR dots in the nuclei of 100 cells and the number of brown nuclei which expressed Ki-67 in 100 cells were studied.
Results:

There was a significant correlation between salivary gland MEC histological grades and number of AgNOR dots. (rs=0.791 , P value=0.00)
A significant correlation was detected between salivary gland MEC histological grades and ki-67 expression. (rs=0.893 , P value=0.00)
The findings in our study (AgNOR dots & ki-67 expression) were slightly different between grades I and II but the difference between the first two grades and the last grade was highly significant.

Conclusion:
Use of any of the two proliferating markers mentioned above (AgNOR and Ki-67) is suitable in detection of histological grades of salivary gland MEC. Considering the highly significant difference between the last grade and the first two grades, MEC classification as low grade and high grade is suggested.