[Glial fibrillary acidic protein and central nervous tumors. Immunohistochemical study of a series of 207 cases. 1: Astrocytomas. Glioblastomas. Ependymomas. Papillomas of the choroid plexus].

The presence of glial fibrillary acidic protein (GFA) was tested in biopsy or autopsy specimens of 207 human central tumors. Samples were fixed, paraffin-embedded and GFA was detected using the peroxidase-antiperoxidase technic. The first part of this study dealt mainly with glioblastomas (36 cases) and astrocytomas (87 cases). Tumors were classified in three categories according to their histological grade: 24 astrocytomas grade I and II, 63 astrocytomas grade III and IV and 36 glioblastomas (grade IV). For each of these tumors GFA positive cells were counted in 5 different fields using objectives of 2,5, 10 and 25. The results were as follows: less than 50% GFA positive cells were found in 22 out of 24 low grade astrocytomas, 49 out of 63 high grade astrocytomas and 32 out of 36 glioblastomas. Conversely, over 50% GFA positivity was found in 2 benign astrocytomas, 14 malignant astrocytomas and 4 glioblastomas. In 3 high grade tumors (2 astrocytomas, 1 glioblastoma) GFA positivity was found to be over 75%. Of the 17 ependymomas, 14 were GFA positive; however, no correlation could be established between the degree of GFA positivity and histological grade. The three papillomas of the choroid plexus of the lateral ventricles found in children were GFA negative. In adults, a GFA positive focus of ependymal differentiation was found in a papilloma of the choroid plexus in the posterior cerebral fossa.