Invasive urothelial carcinoma within a calyceal diverticulum associated with renal stones: A case report.

Calyceal diverticula are rare outpouchings of the upper collecting system lying within the renal parenchyma. These often contain stones, however, carcinoma within a calyceal diverticulum is uncommon. The present study reports a case of invasive urothelial carcinoma within a calyceal diverticulum associated with renal stones. A 70-year-old male with a left renal mass identified by abdominal computed tomography was referred to the Department of Urology, Kanazawa University Hospital. Pre-operative diagnosis was difficult owing to an atypical imaging finding of a hypovascular renal mass with calcification. A laparoscopic nephroureterectomy was performed, and the surgical specimens showed invasive high-grade urothelial carcinoma within a calyceal diverticulum, and the calcifications were renal stones consisting of 97% calcium oxalate. Urothelial carcinoma in calyceal diverticula is a rare condition, however, a pre-operative definite diagnosis is difficult and a high potential for invasion of the renal parenchyma is suspected in this disease.