[Atypical renal cysts: report of 31 cases]

In a series of 205 patients operated for renal cyst, 31 cases had a persistent preoperative doubt concerning the benign nature of the cyst after IVU and/or first-line renal ultrasonography or even computed tomography (80% of cases). Histological confirmation based on analysis of the entire cyst wall or the partial nephrectomy specimen revealed cancer in 45% of cases. Computed tomography must therefore be performed routinely in patients with atypical renal cysts. The authors recommend surgical exploration and partial nephrectomy with frozen section examination at slightest doubt.