SILVER-STAINED NUCLEOLAR ORGANIZER REGIONS (AGNORS) AS A PROGNOSTIC VALUE IN MALIGNANT-MELANOMA

The nucleolar organizer regions (NORs) are chromosomal loops of DNA an d proteins involved in ribosomal synthesis. By silver staining, they c an be identified as black dots (AgNORs) in the nuclei. Their size and number reflect cell and nuclear activity, Therefore, AgNOR count may c orrelate with the proliferative activity of tumors. In malignant melan oma, correlation between AgNOR count and the growth phase was found. H owever, the value of AgNORs in determining prognosis is disputable. Ou r purpose was to evaluate the role of AgNORs in predicting the biologi cal behavior of melanoma. Paraffin-embedded sections of 30 cases of pr imary melanoma, 0.4-5 mm thick (mean, 1.6 mm) were stained with silver . Follow-up of all patients was at least 5 years. For each tumor, at l east 50 cells were randomly selected for AgNOR count at a final magnif ication of 500, and the mean of AgNOR content was calculated. Sample p arameters corresponded well to the epidemiology and the natural histor y of melanoma. AgNOR counts (0.78-4.26; mean, 1.42 +/- 0.72) correlate d with tumor thickness (p = 0.01); thus, most superficial tumors had l ow AgNOR counts, whereas most deep tumors (greater than or equal to 1. 5 mm) showed high counts. Patients who had tumors with AgNOR counts lo wer than the median had longer disease-free interval (DFI) than did pa tients who had tumors with higher counts (p = 0.02). Furthermore, in a multivariate Cox analysis, AgNOR count was independent of tumor thick ness in determining DFI (p = 0.05). Therefore, AgNORs may serve as a p arameter to predict more accurately the progression of melanomas (main ly thin ones). Larger studies art: needed in order to consolidate thes e preliminary results and to characterize AgNOR value further as a pro gnostic factor in melanoma.