Y 90 Ibritumomab Tiuxetan &Rituximab Relapsed or Refractory Diffuse Large B-Cell Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: * Histologically confirmed diffuse large B-cell non-Hodgkin's lymphoma, including any of the following: * B-cell diffuse large cell variant * Immunoblastic * Mediastinal (thymic) large cell * T-cell/histiocyte-rich * Anaplastic large B-cell * Intravascular large B-cell * Lymphomatoid granulomatosis * Relapsed or refractory disease after at least 1 prior chemotherapy regimen and requires further treatment * Relapsed disease, defined as the following: * Appearance of any new lesion OR increase of at least 50% in the size of a previously involved site * 50% increase in greatest diameter of any previously identified node greater than 1 cm in the short axis OR in the sum of the perpendicular diameter (SPD) of more than 1 node * Progressive disease, defined as the following: * 50% increase from nadir in the SPD of any previously identified abnormal node * Appearance of any new lesion during or at the end of therapy * CD20-positive disease by immunohistochemistry * Bidimensionally measurable disease * At least 1 lesion at least 2.0 cm by CT scan * Less than 25% bone marrow involvement by lymphoma * No transformed lymphoma from indolent to aggressive * No HIV- or AIDS-related lymphoma * No hypocellular bone marrow * No marked reduction in bone marrow precursors of 1 or more cell lines (e.g., granulocytic, megakaryocytic, or erythroid) * No CNS lymphoma * Ineligible for myeloablative therapy OR refused transplantation * Ineligible for any other open yttrium Y 90 ibritumomab tiuxetan investigational protocols PATIENT CHARACTERISTICS: Age * 18 and over Performance status * WHO 0-2 Life expectancy * At least 3 months Hematopoietic * Absolute neutrophil count at least 1,500/mm\^3 * Lymphocyte count no greater than 5,000/mm\^3 (for patients with small lymphocytic lymphoma) * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin no greater than 2.0 mg/dL Renal * Creatinine no greater than 2.0 mg/dL Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 1 year after study participation * No concurrent serious nonmalignant disease or infection that would preclude study participation * No human antimurine antibody reactivity PRIOR CONCURRENT THERAPY: Biologic therapy * See Disease Characteristics * No prior autologous bone marrow transplantation * No prior peripheral blood stem cell rescue * No prior failed stem cell collection * Prior rituximab within the past 90 days allowed provided patient has fludeoxyglucose-avid disease that is also indium In 111 ibritumomab tiuxetan-avid disease in at least 1 lesion * More than 2 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy * See Disease Characteristics Endocrine therapy * Not specified Radiotherapy * No prior radioimmunotherapy * No prior external beam radiotherapy (involved field or regional) to more than 25% of active bone marrow Surgery * More than 4 weeks since prior major surgery (except diagnostic surgery) Other * Recovered from all prior therapy * More than 4 weeks since prior therapy for lymphoma * More than 8 weeks since prior phase II investigational drugs * No other concurrent antineoplastic therapy