Nucleolar organiser regions: new prognostic variable in breast carcinomas.

Nucleolar organiser regions (NORs), which are important for regulating protein synthesis, were identified in 20 breast carcinomas by means of a silver (Ag) staining technique. Infiltrating neoplasms with metastases in four or more axillary lymph nodes possessed, on average, a greater number of AgNORs per cell nucleus compared with neoplasms without nodal disease, or with one to three positive lymph nodes. The size, morphology, and distribution of AgNORs within the nucleus were also different in the two study groups. Overall, these findings suggest that breast carcinomas with multiple, irregular, and widely dispersed AgNORs tend to be of high grade malignancy.