RESUMEN
A 72-year-old man referred our hospital with the chief complaint of macroscopic hematuria. He had undergone simple left nephrectomy for left renal stone when he was 27-years-old. His urine cytology showed class IIIb. They were 4 times. We performed random biopsy of the bladder and retrograde pyelography of the right But they were no positive findings for the cause of hematuria and for the existence of malignancy. After 2 months, he had macroscopic hematuria again. Cystoscopic re-examination revealed a fibrin out of the residual left ureteral orifice. Computed tomographic scan showed a perivesical mass. The diagnosis was the carcinoma of the ureteral stump. We performed ureterectomy. The pathological study revealed the undifferentiated carcinoma. This case is the first report of the undifferentiated carcinoma occurred on the residual ureteral stump in the Japanese literature.