OBJECTIVES: I. Assess the efficacy and treatment-related toxicity of high-dose chemotherapy comprising carmustine, etoposide, cytarabine, and melphalan followed by autologous peripheral blood stem cell transplantation in patients with primary central nervous system lymphoma. II. Determine the safety of this regimen in these patients. III. Determine the efficacy of this regimen, in terms of 2-year disease-free survival, in these patients. IV. Assess neurologic outcome using serial neurologic examinations in patients treated with this regimen.