Inflammatory pseudotumor (IPT) is a tumor-like reactive lesion of unknown etiology. An unusual case of intracardiac IPT with multisystemic involvement, including leukocytoclastic vasculitis, polyarthritis, and inferior vena cava thrombosis in a 17-year-old boy is reported. This unique combination may suggest that immune/autoimmune factors are important in the pathogenesis of IPT.