Transitional cell carcinoma within a calyceal diverticulum associated with stone disease.

We report a case of transitional cell carcinoma (TCC) discovered within a calyceal diverticulum at the time of percutaneous nephrolithotomy. The stones and tumor were endoscopically removed and the diverticular cavity fulgurated. Pathologic analysis demonstrated low-grade TCC. A subsequent laparoscopic radical nephroureterectomy was performed and high-grade TCC invading the parenchyma was found. This case demonstrates the potential for TCC to develop in stone-containing calyceal diverticula and also the potential for coexistence of different grades of TCC within the involved renal unit.