Inflammatory pseudosarcoma (pseudotumor) of the bladder. Inflammatory pseudosarcoma of the bladder is a rare benign entity that cannot be differentiated from malignant tumor at radiologic examination alone. Only pathologic examination can enable a definitive diagnosis. The authors report two cases of these benign tumors in patients with no history of bladder disease or trauma; the tumors were large, demonstrated invasion into local tissues, and recurred in one case after incomplete transurethral resection. 