FIG 1. Histopathologic section from biopsy sample obtained in patient 2. A few neuronal cells are visible (arrows), surrounded by astrocytes with hyperchromatic nuclei in a fibrillar eosinophilic background. Immunohistochemical study has shown that the tumoral cells express the GFA protein; the KI-67 index was low. No necrosis or mitotic figures or endothelial proliferation were observed. These elements are consistent with the diagnosis of astrocytoma grade II (WHO, 1993). Scale bar: 60 µm. Hematoxylin erythrosin saffron.