Intrathecal Rituximab in Lymphoid Malignancies Involving Central Nervous System

Study Groups and Study Drug Administration: If you are found to be eligible, you will be assigned to a study group based on when you join this study. Up to 12 participants will be enrolled in the Phase I portion of the study, and up to 13 participants will be enrolled in Phase II. If you are enrolled in the Phase I portion, the dose of rituximab you receive will depend on when you joined this study. The first group of participants will receive the lowest dose level of rituximab. Each new group will receive a higher dose of rituximab than the group before it, if no intolerable side effects were seen. This will continue until the highest tolerable dose of rituximab is found. If you are enrolled in the Phase II portion, you will receive rituximab at the highest dose that was tolerated in the Phase I portion. Study Visits: Once enrolled, you will return to the clinic and receive the study drug by spinal tap up to 2 times a week. You will receive treatment twice a week until 2 CSF samples in a row do not show any leukemia cells. After that, you will receive treatment 1 time a week for an additional 4 weeks, and then you will receive treatment once every other week for an additional 8 weeks. The number of doses you receive will depend on how many doses the study doctor thinks is needed. At each study visit the following procedures will be performed: * You will have a physical exam, including measurement of your weight, and vital signs. °Your vital signs will be measured every 15 minutes for 1 hour after each dose of rituximab. * You will be asked how well you are able to perform the normal activities of daily living (performance status). * You will be asked about any drugs you may be taking and any side effects you may experiencing. * Blood (about 2 tablespoons) will be drawn for routine tests. * A sample of cerebral spinal fluid may be collected from the lumbar puncture to verify the absence or presence of blast cells. Follow-Up: About 30 days after your last dose of study drug you will be contacted by the study staff by telephone and asked about any drugs you may be taking and any side effects you may experiencing. This call should take about 10 minutes. Long-term Follow-up: Every 6 to 12 months you may be contacted by the study staff by telephone and asked about any drugs you may be taking and any side effects you may experiencing. This call should take about 10 minutes. You may be given other drugs to help prevent side effects. The study staff will tell you about these drugs, how they will be given, and the possible risks. Length of Treatment: The number of treatments you receive will depend on how long it takes for there to be no leukemia cells in the CSF samples. Once this happens, you will have treatments for an additional 12 weeks. You will no longer be able to take the study drug if the disease gets worse, if intolerable side effects occur, or if you are unable to follow study directions. This is an investigational study. Rituximab is FDA approved and commercially available for the treatment of relapsed and/or refractory lymphoid malignancies involving the central nervous system. Receiving rituximab by spinal tap is considered investigational. Up to 25 patients will take part in this study. All will be enrolled at MD Anderson.