Oligodendroglioma and Oligo-Astrocytoma

Abstract Oligodendroglioma was initially classified in 1926 by Bailey and Cushing1 and was considered to be a differentiated form of medulloblastoma. Three years later, Bailey and Bucy,2 applying a new histological technique developed by Rio-Hortega, proved the presence of oligodendroglia in oligodendrogliomas, and reclassified the tumor to glial lineage. Oligodendroglioma is composed of oligodendroglia (>80%); if greater than 20% of the cells are astrocytic, the tumor is an oligo-astrocytoma.