 RATIONALE: Drugs used in chemotherapy work in different ways to stop tumor cells from dividing so they stop growing or die. Combining chemotherapy with stem cell transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more tumor cells. Monoclonal antibodies, such as rituximab, can locate tumor cells and either kill them or deliver tumor-killing substances to them without harming normal cells. It is not yet known whether stem cell transplantation is more effective with or without rituximab in treating relapsed or progressive B-cell diffuse large cell lymphoma. 