 - The subject may have had other systemic chemotherapy for PCNSL during the 90 days since PCNSL diagnosis; prior systemic chemotherapy must have been given at least 4 weeks prior to study entry 6 weeks for nitrosourea agents, with the exceptions of methotrexate and rituximab which may have been given at least 10 days prior; ocular lymphoma treatment may have been given any time prior to study entry; if the subject has undergone treatment for parenchymal disease and the parenchymal disease has progressed on a stable or increasing dose of steroids, the subject is not eligible for enrollment 