Nucleolar organizer regions in FNAC smears of breast lesions.

The argyrophil technique for staining proteins associated with nucleolar organizing regions was applied to the fine-needle aspiration cytology smears of 45 cases of breast disease. These included 14 malignant and 31 benign lesions. A correlation with histology sections was done in 12 cases. There was a significant difference between AgNOR count of benign and malignant breast disease with one case out of 45 falling in the "gray" zone of overlap. Infiltrating lobular carcinoma was found to have the lowest NOR counts among the malignant lesions. The smear staining was superior to that on sections, the positive features being lack of background staining and better dispersion of NORs in the nucleoli.