NUCLEOLAR ORGANIZER REGIONS IN OPTIC GLIOMAS

The biological nature of optic gliomas is controversial, with some con sidering them benign hamartomatous lesions, and others believing them to be true neoplasms. We evaluated the use of colloid silver impregnat ion of nucleolar organizer region-associated proteins (AgNORs) in maki ng this distinction. Thirty-one optic gliomas, 14 optic nerve meningio mas, and a single case of giant cell glioblastoma multiforme (monstroc ellular glioma) of the optic chasm were stained for AgNORs and counted in a masked fashion. The optic gliomas contained 2.01 +/-0.09 AgNORs per nucleus, similar to that of optic nerve meningiomas (2.15 +/-0.15) and our previously reported counts for diffuse fibrillary astrocytoma (2.22+/-0.10), and significantly more than that of reactive astrocyto sis (1.18+/-0.02). Six of the seven optic gliomas examined had compoun d AgNORs, a feature associated with malignancy in other tumour types. AgNOR counts did not correlate with clinical features, including those seen during the post-operation course. These data suggest that optic gliomas may be true neoplasms, and not benign hamartomas.