Nucleolar organizer regions in smooth muscle and breast tumours.

Paraffin sections of formalin fixed tissues, obtained from patients with smooth muscle and breast tumours, were studied by the silver staining technique to quantitate the Nucleolar Organizer Regions (AgNORs) per nucleus and to assess its significance as an independent variable in predicting the behaviour of these neoplasms. Five benign and five malignant tumours of smooth muscle along with ten benign and ten malignant epithelial tumours of breast were studied. Normal myometrium and breast tissue served as controls. Control, benign and malignant tumours of smooth muscle showed mean AgNOR scores of 2.68, 3.89 and 12.50 per nucleus respectively. Control, benign and malignant tumours of breast showed mean AgNOR scores of 1.75, 7.45 and 12.72 per nucleus respectively. These results suggest that quantitative analysis of AgNORs per nucleus is capable of differentiating benign from malignant lesions of smooth muscle and breast.