Squamous cell carcinoma in a duplicated renal pelvis.

We report an extremely rare case of squamous cell carcinoma (SCC) of the renal pelvis associated with an incompletely duplicated renal pelvis and ureter. A 71-year-old woman presented with left lower back pain and gross hematuria. Urinary cytology showed atypical squamous cells. Computed tomography, magnetic resonance imaging and retrograde pyelography revealed left incompletely duplicated renal pelvis and ureter and a mass in the left upper renal pelvis. A clinical diagnosis of left renal pelvic cancer was made and the patient underwent total nephroureterectomy. Histological examination of the resected specimen revealed SCC with marked keratinization in the upper renal pelvis. The tumor had invaded the renal parenchyma and perinephric fat. There was no urothelial carcinoma component. The pathological stage was pT4 N0. There was no evidence of recurrence 6 months postoperatively. Because the prognosis of SCC of the upper urinary tract is poor, urologists and pathologists should be aware that SCC may develop in duplicated urinary systems.