ABSTRACT
Introduction: Intravascular large B-cell lymphoma (IVLBCL) is a rare disease entity of non-Hodgkin lymphoma. Patients with IVLBCL frequently have neurological symptoms associated with cerebrovascular infarction or central nervous system involvement of malignant lymphoma. Case: A 67-year-old man consulted the Department of Hematology at our hospital because of fever of unknown origin, anemia and increased serum lactate dehydrogenase. Although IVLBCL was strongly suspected, no lymphoma cells were found by multiple bone marrow aspirations and skin biopsies. Two months later, he developed hyperactive delirium, which was difficult to manage using antipsychotic agents. Brain MRI revealed multiple hyper-intense infarct-like lesions on diffusion-weighted images. After assessment of bone marrow aspiration and skin biopsies, he was administered an enough dose of prednisolone to manage malignant lymphoma. Hyperactive delirium rapidly improved. Discussion: In patients with IVLBCL, corticosteroids may be useful to manage hyperactive delirium due to cerebrovascular infarction or central nervous system involvement of IVLBCL.