A characteristic clinical course of a patient with micropapillary bladder cancer, a rare histological variant with high metastatic potential, is presented. An 80-year-old woman had locally advanced high-grade bladder cancer with a focal micropapillary variant identified which was treated with intra-arterial chemotherapy with radiation therapy. Standard follow-ups involving cystoscopy with cold-cup biopsies and computed tomography could not detail the bladder carcinoma; however, the patient died of carcinomatosis 20 months after treatment. At autopsy, carcinomas proliferated under benign mucosa and infiltrated diffusely in the retro peritoneum. This behavior differs from the normal pattern of invasive transitional cell carcinoma, which usually proliferates forming a mass lesion. Thus, it may be difficult to detect micropapillary bladder cancer by computed tomography which demonstrates only increased tissue density in retroperitoneal fascia; therefore, care should be taken in the follow-up of micropapillary bladder cancer.