[Transitional cell carcinoma of the ureter with inverted proliferation: a difficult case to make a differential diagnosis with ureteral polyp].

A 59-year-old man was admitted to our hospital in June 2001 for evaluation of an asymptomatic microscopic hematuria. One year prior to presentation, he had a spontaneous discharge of a left ureteral stone. Excretory urography and retrograde pyelography showed a filling defect in the middle portion of the left ureter. Cystoscopic examination did not reveal any abnormality, and urinary cytology was class I. Cold cup biopsy was performed under ureteroscopy, and pathology revealed inflammatory fibrovascular tissue but with no malignancy. Selective washing cytology was class III, whereas selective washing cytology done at the referring hospital was reported to be class V. Under a preoperative diagnosis of a left fibroepithelial ureteral polyp or a transitional cell carcinoma, left segmental ureterectomy was performed. The tumor was 5 x 5 x 5 mm in size, pedunculated, and smooth-surfaced. Intraoperative pathological examination of a frozen section showed an inverted type transitional cell carcinoma. Therefore, a left nephroureterectomy was performed, and the final histopathological examination confirmed an inverted type transitional cell carcinoma of grade 2. The patient is healthy and free of disease 15 months after operation. We also reviewed the current literature relating to transitional cell carcinomas of the ureter with inverted proliferation.