Signet ring cell carcinoma in adenomatous polyp at site of ureterosigmoidostomy 16 years after conversion to ileal conduit.

The case of a signet ring cell carcinoma of the colon arising in an adenoma at the site of ureterosigmoidostomy after conversion to an ileal conduit is reported. Urine exposure to the colonic mucosa was present only for a short period before development of an adenoma with subsequent signet ring cell carcinoma transformation more than 15 years later. In the face of recent reports on adenocarcinoma in cases of bladder substitution or augmentation without any possible promoting influence of the fecal stream, the well known risk of neoplasia after sigmoidostomy remains unclear in its etiology.