Significance of nucleolar organizer regions in differentiation between benign tumours and their malignant counterparts

Nucleolar organizer regions [NORs] represent nuclear activity in both normal and malignant cells. Using the argyrophilic technique on routinely processed formalin fixed paraffin sections, NORs appear as black dots. In the present work, benign tumors and their malignant counterparts in several organs [skin, colon, thyroid and prostate] have been studied. It was found that there is a significant increase in the mean number of AgNORs [X] in malignant cases [X = 5.95] which is more than their benign counterparts [X = 2.8] except in pilomatrixoma where the mean number was 10.3, 10.5. In dysplastic colonic polypi, the topographic distribution of NORs was similar to that found in well differentiated adenocarcinoma of the colon but still having a statistically significant difference in their count. So, NORs count could be useful in distinguishing between benign, dysplastic and malignant lesions of the skin, colon, thyroid gland and prostate

Prognostic value of nucleolar organizer regions in urothelial carcinoma in relation to grading and staging

Using a silver staining technique, nucleolar organizer regions were identified in routinely processed paraffin sections of 40 cases of epithelial urinary bladder lesions. The technique shows argyrophilic NOR associated proteins [AgNORs], which are seen in nuclei as black dots. There was a significant difference between benign urothelial hyperplasia and carcinoma [t=5.301] as well as between the different grades of urothelial carcinoma; grade 1 and 2 [t=4.697] and grade 2 and 3 [t=5.717], where there was an inverse relationship between the number of AgNORs and degree of differentiation. There was no significant difference between in situ and grade 1 urothelial carcinoma. [t=0.323]