Intravascular lymphoma (IVL) is an uncommon neoplastic disorder characterized by monoclonal intravascular expansion of lymphoid cells. Occlusion of small vessels in various organ systems probably accounts for the broad clinical spectrum of this type of lymphoma, which can closely mimic a variety of diseases, especially vasculitic disorders, and thus lead to delayed clinical diagnosis. This is the first report of a patient who presented with a predominant symptom of symmetric polyarthritis accompanied by fever. While her initial systemic symptoms, such as fever, improved rapidly after initiation of corticosteroid therapy, the response of the polyarthritic joint manifestations was only transient. The patient died of progressive lung involvement and was diagnosed as having IVL by histologic analysis of tissue samples obtained postmortem.