Intravascular large B-cell lymphoma (IVLBCL) involving kidney. Medium to large-sized neoplastic lymphocytes are seen clogging the blood vessels in between renal tubules. The etiology of IVLBCL is unknown. The preferential localization of tumor cells within vascular spaces is at least partly related to the loss of expression of CD29 (beta-integrin) and CD54 (ICAM-1). These two markers play a role in transvascular lymphocyte migration.