A. Barzilai et al., SILVER-STAINED NUCLEOLAR ORGANIZER REGIONS (AGNORS) AS A PROGNOSTIC VALUE IN MALIGNANT-MELANOMA, The American journal of dermatopathology, 20(5), 1998, pp. 473-477
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.