In intravascular lymphomas, the neoplastic cells preferentially proliferate within small blood vessels, especially capillaries and post-capillary venules. The clinical presentation shows some geographic variations. Cases diagnosed in Western countries have a high frequency of CNS and skin involvement, whereas patients from Asian countries are more likely to present with hemophagocytic syndrome, bone marrow involvement, fever, hepatosplenomegaly, and thrombocytopenia. The image shows a case with renal involvement. The smaller blood vessels are engorged with neoplastic lymphocytes. Reference: Maurilio Ponzoni et al. Definition, diagnosis, and management of intravascular large B-cell lymphoma: Proposals and perspectives from an international consensus meeting. J Clin Oncol 25:3168-3173, July 2007.