After induction therapy, patients achieving complete response, very good partial response, or partial response receive consolidation therapy comprising melphalan IV on days -7 to -5 followed by carboplatin IV and etoposide IV continuously over days -7 to -4. Patients receive purged or unpurged PBSC infusion or purged autologous bone marrow transplantation on day 0 followed by G-CSF SC or IV beginning 4 hours after completion of transplantation and continuing until blood counts recover. Beginning on day 66, patients receive oral isotretinoin twice daily for 14 days. Isotretinoin therapy repeats every 4 weeks for 6 courses.