Methotrexate, Cyclophosphamide, and Etoposide Phosphate Given With Osmotic Blood-Brain Barrier Disruption Plus Dexamethasone and Cytarabine in Treating Patients With Primary CNS Lymphoma

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed intermediate- or high-grade primary CNS lymphoma by brain biopsy or cerebrospinal fluid or vitrectomy analysis * No more than 90 days since diagnosis * No systemic lymphoma NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology. PATIENT CHARACTERISTICS: Age * 16 to 75 Performance status * ECOG 0-3 OR * Karnofsky 40-100% Life expectancy * Not specified Hematopoietic * Hematocrit at least 25% (transfusion allowed) * WBC at least 2,500/mm\^3 * Absolute granulocyte count at least 1,200/mm\^3 * Platelet count at least 100,000/mm\^3 OR at least lower limit of normal (transfusion independent) Hepatic * Bilirubin no greater than 2.0 times upper limit of normal Renal * Creatinine clearance at least 30 mL/min Cardiovascular * Adequate cardiac function to tolerate general anesthesia Pulmonary * Adequate pulmonary function to tolerate general anesthesia Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception for 2 months before and during study participation * No other uncontrolled clinically significant confounding medical condition within the past 30 days * No known allergy to study agents * HIV negative PRIOR CONCURR…