[Tumor of the urinary tract and renal lithiasis. Apropos of 4 cases].

The authors present four observation of renal lithiasis associated with a tumor of the upper urinary tract. The rarity of this association and the facility to only consider lithiasis often conceal the tumor. They define the "high risk lithiasis" for which CT-scan is mandatory. Tumor of the urinary tract has to be treated and the prognosis becomes less favorable.