RÉSUMÉ
BACKGROUND: In ganglion cell tumos, immunohistochemical characteristics and malignant changes of neuronal cells and the usefulness of the MIB-1 (Ki67) indices for granding ganglion cell tumors and abnormalities of the adjacent nonneoplastic cortex have been issued. METHODS: The clinicopathologic features of 34 surgically resected ganglion cell tumors (32 gangliogliomas and 2 gangliocytomas) were retrospectively analysed, and immunohistochemical characteristics and malignant changes of neuronal cells and the usefulness of the MIB-1 (Ki67) indices for grading ganglion cell tumors and abnormalities of the adjacent normal cortex were investigated using various immunohistochemical studies. RESULTS: According to the Daumas-Duport grading system, there were 24 (70.6%) grade II, 8 (23.5%) grade III, and two (5.9%) grade IV cases. Malignant transformation was present only in the glial (7 cases) or both glial and neuronal (3 cases) components. The MIB-1 indices were statistically significant (p<0.001): grade II was 0.0-1.05% (0.27+/-0.3%), grade III was 0.8-8.02% (2.8+/-3.2%), and grade IV was 3.0-4.99% (3.99+/-1.0). Anaplasia and MIB-1 positivity was observed among the neurons in the three cases. Perikaryal cytoplasmic expression or surface punctate accentuation of synaptophysin were noted only in the neoplastic neurons in some cases. Fifteen out of 20 cases, which included the nonneoplastic cerebral cortex, displayed mild cortical dysplasia (microdysgenesis). CONCLUSIONS: The neuronal component also showed malignant transformations with proliferating activity. In our study, synaptophysin-immunoreactive patterns of neoplastic neurons were unique. The MIB-1 indices were helpful for grading ganglion cell tumos. Only mild cortical dysplasia was present in the normal cortex adjacent to the tumor.