Comparative study of the degree of differentiation of neuroblastoma and mean numbers of nucleolar organiser regions.

Twenty confirmed cases of childhood neuroblastoma diagnosed over six years were reviewed and classified according to the subtyping proposed by Shimada et al. The tumours were stained using a silver colloid method for nucleolar organiser regions (NORs), and the mean number of NORs for every 200 cells was calculated. The correlation between the mean number of NORs and histology and survival was studied. There was a significant correlation between the mean numbers of NORs and differentiation, and with the mitosis-karyorrhexis index (MKI) in the stroma poor group (p = 0.01-0.001). A trend to increased survival with decreased numbers of NORs was observed in the study group as a whole (rank order of correlation = -0.57, p = 0.05-0.02). It is suggested that mean number of NORs is of prognostic value in neuroblastomas.