After regimen A, B, or C and in the absence of disease progression, patients undergo consolidation myeloablative chemotherapy by receiving carboplatin IV over 4 hours on days -8, -7, and -6, and then thiotepa IV over 3 hours followed by etoposide IV on days -5, -4, and -3. Patients with malignant gliomas or unbiopsied diffuse intrinsic pontine tumors do not receive etoposide. On day 0, patients are reinfused with autologous PBSC. Following recovery from consolidation chemotherapy, patients with radiographic or cytologic evidence of residual disease undergo radiotherapy.