[Value of the nucleolar organizers (AgNOR) in brain gliomas]

The aim of the study was to evaluate the feasibility and possible contribution of silver stained nucleolar organizer regions (AgNORs) to prognostic considerations, in a series of 55 supratentorial gliomas: eight grade II astrocytomas, twelve grade III astrocytomas, thirty grade IV astrocytomas, two glioblastomas, one anaplastic oligodendroglioma, one oligodendroglioma and one ependymoma. Silver NORs (AgNORs) were demonstrated according to the method of Crocker et al. A difference between AgNOR sizes in peritumor and tumor tissue is noted. The mean NOR numbers in the tumor areas range from 0.871 to 2.677, without overlap between peritumor gliosis and glial tumors. A comparative analysis reveals significant correlations between the mean NOR number per nucleus and histological grading. This technique can play a practical role in the diagnosis and grading of tumors sampled by stereotactic biopsies: a count higher than 0.8 is highly suggestive of malignancy. In addition, the distribution of NORs may be important: intratumoral heterogeneity expresses various degrees of transcriptional activity between different glial tumors of the same grade. This technique provides information about the biological behaviour of glial tumors supplementary to that obtained from growth fraction analysis.