Treating Patients With Recurrent PCNSL With Carboplatin/BBBD and Adding Rituxan To The Treatment Regimen

INCLUSION CRITERIA: * Signed informed consent form in accordance with institutional guidelines * Histologically or cytologically confirmed primary CNS lymphoma documented by brain biopsy or cerebrospinal fluid or vitrectomy analysis * CD20 positive disease * Progressive or relapsed disease during or after completion of prior methotrexate-based chemotherapy * Aged 18 months to 75 years * Performance status ECOG 0-3 OR Karnofsky 30-100% * Hematocrit at least 25% (transfusion or epoetin alfa allowed) * Absolute granulocyte count at least 1,200/mm\^3 * Platelet count at least 100,000/mm\^3 OR at least lower limit of normal * Bilirubin no greater than 2.0 times upper limit of normal * Creatinine less than 1.8 mg/dL * Calculated Creatinine clearance (CrCl) at least 50 mL/min * Adequate cardiac function to tolerate general anesthesia * Adequate pulmonary function to tolerate general anesthesia * Available for follow-up for 1 year post therapy * Fertile patients must use effective contraception for a minimum of 2 months before and during study participation EXCLUSION CRITERIA: * Radiographic signs of intra-cranial herniation and/or spinal block * HIV positive * Systemic lymphoma * Positive serum HCG, pregnant or lactating * Allergy to study agents * Hepatitis B or hepatitis C positive