Renal pelvic carcinoma of horseshoe kidney caused systemic metastasis by implantation in prostate.

A case is reported of renal pelvic carcinoma of the horseshoe kidney in a 69-year-old man, which showed an interesting metastatic pattern by implantation in the prostate. A few months after transurethral resection of the prostate for benign prostate hyperplasia and extracorporal shock wave lithotripsy for renal stones, the patient complained of severe back pain due to multiple metastatic bone tumors. Autopsy revealed transitional cell carcinoma in the pelvis as well as in the prostate with remarkable vessel invasion. The clinical course and autopsy findings suggested that the systemic expansion of cancer cells from the renal pelvis was caused not only by direct metastasis but also by implantation in the prostate.