[Efficacy of preoperative irradiation in midline oligodendrogliomas. Report of two cases]

Two midline oligodendrogliomas in young males were successfully totally removed after preoperative irradiation. A 33-year-old male with right lower extremity weakness had a large hypervascular mass occupying the left lateral ventricle. Even after 31 Gy whole-brain irradiation, massive bleeding occurred at surgery and resulted in only partial removal. The residual tumor markedly regressed with disappearance of abnormal vascularity after subsequent local boost irradiation. At the second operation, the tumor was totally removed. A 32-year-old male with progressive headache had a hypervascular mass with gross calcification in the right lateral ventricle. The tumor was partially resected due to its abundant vascularity and blood loss. After 60 Gy local irradiation, the tumor was moderately shrunk with a significant reduction in vascularity. At the second operation, the tumor was totally removed. Preoperative irradiation as an adjunct to surgery may increase the resectability of highly vascular tumors such as midline oligodendrogliomas.