Nucleolar organizer regions in aggressive and nonaggressive basal cell carcinoma of the skin

Nucleolar organizer regions (NOR) were investigated on routine paraffin-embedded histologic sections of 11 aggressive basal cell carcinomas that recurred and/or metastasized (BCC2) and 11 nonaggressive basal cell carcinomas (BCC1). The absolute number of NOR per nucleus was higher in BCC2 than in BCC1, and their distribution pattern was also different. In fact, the means of argyrophilic staining of NOR (AgNOR) counts in the two groups of tumors by two observers were 6.56 with a SD of 1.98 for the nonaggressive and 9.48 with a SD of 2.12 for the aggressive basal cell carcinomas. A statistical analysis of these data using the Student's t test confirmed these observations (t = 64.49). Problems in the evaluation of NOR and possible comparison with other experiences are also discussed. The authors conclude that a quantitative assay of AgNOR and perhaps their distribution pattern may provide information useful to recognize BCC2 and hence may be of help in their prognostic prediction.