Implantation of colon cancer cells onto renal pelvic mucosa. A case report.

We report here on a patient with recurrent sigmoid colon carcinoma. Postmortem examination revealed a fist-sized tumor in the retroperitoneum, invasive to the left ureter obstructing its lumen causing hydronephrosis of the ipsilateral kidney. Histological examination of the kidney showed multiple foci of adenocarcinoma cells on the pelvic surface. Invasion into the underlying tissue was not observed, and there was no tumor in the submucosal tissue of the pelvis or in the parenchyma of the left kidney. Cancer cells on the renal pelvic mucosa showed strong immunoreactivities for CEA and CA 19-9. These findings suggest that the tumor foci in the pelvis are formed by the intraluminal implantation of colon cancer cells detached from the ureteric metastasis. Our case presents the possibility of the implantation of carcinoma cells in the human urinary tract.