RATIONALE: Drugs used in chemotherapy, such as carboplatin, thiotepa, and etoposide, work in different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy with autologous stem cell transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more tumor cells. Isotretinoin may be effective in preventing recurrence of glioma. It is not yet known which regimen of chemotherapy plus autologous stem cell transplantation with or without isotretinoin is more effective in treating recurrent high-grade glioma.