[The reliability of needle puncture in the diagnosis of benign renal cysts? (author's transl)].

Confirmation of the diagnosis of a benign renal cyst through needle puncture is being reported with increased frequency. The puncture reveals either a clear, cloudy or bloody fluid, or no fluid at all. The authors analyze 88 of their own and 805 cyst punctures from the literature. A benign cyst was always present when the aspirated fluid was clear (763 cases). When the aspirated fluid was cloudy or bloody (130 cases) a malignant kidney tumor was found in 35% of the cases. Complications from cyst punctures are described. The authors feel that needle puncture is a highly effective method in the differential diagnosis of renal masses. It can also be used when multiple cysts are present on one or both sides.