[Histogenesis of subependymal glioma in Bourneville's tuberous sclerosis].

The phenotypic characteristics of 7 subependymal giant cell astrocytomas (GSECG) (6 of these being associated with tuberous sclerosis) are studied using morphological and immunohistochemical methods with antiserums against vimentine, glial fibrillary acid protein (GFA), S100 protein, and neurofilaments. The glycoproteic secretion of the tumor cells was also analyzed after exposure to Concanavalin A (CON A) by a direct fluorescent method. Our results suggest that some GSECG originate from specialized ependyma (circum-ventricular organs). They have the same location (foramen of Monro), present some common ultrastructural features (cytoplasm with lumen containing cilia), are positive with certain immunohistochemical markers (staining with S100 protein in 4 cases, with vimentin in 3 cases) and show a strong glycoproteic secretion (positive with CON A). Therefore, some GSECG might be considered hamartomas of specialized ependyma, with a reduced evolutivity potential.