Rituximab and Yttrium Y 90 Ibritumomab Tiuxetan in Treating Patients With Recurrent Primary CNS Lymphoma

DISEASE CHARACTERISTICS: * Histologically confirmed non-Hodgkin's lymphoma (NHL) * Recurrent disease * Isolated CNS relapse of systemic NHL allowed * Primary CNS lymphoma * Measurable gadolinium-enhancing lesion on MRI of the brain * No impaired bone marrow reserve * No hypocellular bone marrow * No marked reduction in bone marrow precursors of one or more cell lines (granulocytic, megakaryocytic, erythroid) * No pleural effusion * No chronic lymphocytic leukemia * No AIDS-related lymphoma PATIENT CHARACTERISTICS: Age * Adult Performance status * Not specified Life expectancy * Not specified Hematopoietic * Platelet count \> 100,000/mm\^3 * Absolute neutrophil count ≥ 1,500/mm\^3 Hepatic * Bilirubin ≤ 2.0 mg/dL Renal * Creatinine ≤ 2.0 mg/dL Other * HIV negative * No serious nonmalignant disease that would preclude study participation * No infection * No anti-murine antibody reactivity\* * No human anti-mouse antibodies * Not pregnant * Negative pregnancy test NOTE: \*Results must be available prior to study entry for patients who received prior murine antibodies or proteins, other than rituximab PRIOR CONCURRENT THERAPY: Biologic therapy * See Radiotherapy * No prior stem cell transplantation * No prior myeloablative therapies with autologous bone marrow transplantation or peripheral blood stem cell rescue * No prior failed stem cell collection * More than 2 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy * No more than 1 prior chemotherapy regimen Endocrine therapy * Not specified Radiotherapy * No prior radioimmunotherapy * No prior whole-brain radiotherapy * No prior external beam radiotherapy (involved field or regional) to \> 25% of active bone marrow Surgery * More than 4 weeks since prior major surgery except diagnostic surgery