Intravascular lymphomatosis (IVL) is a rare type of lymphoma with a poor prognosis. Its distinctive clinical and histopathologic features are generated by the proliferation of neoplastic mononuclear cells within blood vessels. We describe a patient with IVL of the skin as a manifestation of a recurrent diffuse large B-cell lymphoma of ureteral origin. Lymphoma cells were located both within the vessels and the parenchyma in an early cutaneous lesion. After recurrence in the skin, lymphoma cells gradually located only in the vascular lumina. This transition suggests that cells localized within the vessels were selected as a consequence of chemotherapy. Immunohistochemical examination revealed that the expression of surface adhesion molecules of lymphoma cells did not significantly change. The results of polymerase chain reaction revealed that the ureteral and cutaneous tumors were identical in clonality. Our findings suggest that conventional diffuse large B-cell lymphoma can change into IVL. (J Am Acad Dermatol 2003;48:S1-4.)