[Bladder recurrence of renal cell carcinoma: report of two cases]

We present two rare cases with renal cell carcinoma which recurred at urinary bladder. The first case is an 87-year-old female who had been undertaken right nephrectomy 17 years earlier. Through the examination of hypercalcemia, bone metastases and a bladder tumor were found. Transurethral resection of the bladder tumor was performed and histological examination revealed that the tumor was clear cell carcinoma similar to the right renal tumor. The second case is a 67-year-old male who had been undertaken left nephrectomy 4 and half years earlier. In spite of the adjuvant immunotherapy including interferon alpha, gamma and interleukin-2, 16 months later multiple lung metastases appeared. One month before admission he noticed asymptomatic hematuria. Cystoscopy revealed 3 non-papillary pedunculated tumors, which were resected transurethrally. Histologically the tumor was clear cell carcinoma similar to the left renal tumor. In both cases the metastasis was confirmed histologically. As in both cases the recurrent bladder cancers were confined in the mucosa, these metastases were thought to be caused by implantation.