[Unusual mesenchymal mixed tumors in the kidney region]

On the basis of four cases of extensive benign mesenchymal renal tumours (angiomyolipomas), of which three were histologically ascertained and the fourth was detected during the diagnostics of a case of Pringle-Bourville's disease, the general symptoms as well as the problems of the angiography in benign renal tumours are explained. The coordination of the angiomyolipomas to the choristomas is discussed. It is referred to a conservative-surgical approach in small tumours and to long-term controls, respectively, in clinically symptomless incidental findings.