PROGNOSTIC-SIGNIFICANCE OF NUCLEOLAR ORGANIZER REGIONS (NORS) IN MALIGNANT-MELANOMA

Nucleolar organizer regions (NORs) are loops of ribosomal DNA (rDNA) i n the nucleolus and are associated with acidic proteins. They are seen in routinely processed paraffin sections by using a one-step colloida l silver (Ag) staining method; they appear as black dots termed ''AgNO Rs''. The quantitative assay of AgNORs has been used to differentiate benign from malignant neoplasms. Melanocytic lesions differ significan tly in AgNOR counts between malignant melanoma and nevi. However, conf licting results have been reported as to AgNORs' prognostic value in m elanoma. A recent study showed AgNOR counts to be a more accurate prog nostic indicator than Breslow's thickness. In this study, we counted t he AgNORs in 26 patients with primary cutaneous melanomas (CMM) betwee n 2.0 mm and 2.5 mm thick. Of these, 14 are alive without disease (AN) at 5 years after diagnosis (group 1), and 12 are dead of disease (DD) in less than 5 years (group 2). The AgNORs were scored in 30 nuclei p er tumor, and the means were calculated. For group 1, the mean number of AgNORs per nucleus was 6.88, ranging from 3.73 to 12.70. For group 2, the mean number was 6.97, ranging from 3.63 to 11.67. Statistical a nalysis using analysis of variance (ANOVA) showed no significant diffe rence between the groups (p=0.33). In our study, AgNOR counts did not prove to be of prognostic value in malignant melanoma.