Intravascular large B-cell lymphoma (IVLBCL) is a DLBCL in which medium- to large-sized neoplastic B-cells infiltrate small- to medium-sized blood vessels and sinusoids in the liver, spleen, and/or bone marrow. IVLBCL may be associated with the hemophagic syndrome (i.e. excessive cytokine secretion and systemic inflammation). Patients afflicted with the latter syndrome have very short survival times. The poor prognosis of this disease has been significantly improved by rituximab or similar immunochemotherapy drugs but significant proportions of these responding cases relapse, often with central nervous system involvement.