[Cystic tumors of the kidney in adults: radio-histopathologic correlations].

The purpose of this study is to provide an updated pathologic-radiologic classification of cystic renal tumors and to assess imaging diagnostic capabilities. Eighty seven cases of cystic renal tumors explored with multimodality imaging (ultrasonography, CT, MRI, arteriography) and with histopathologic correlation are reported. The most common cystic carcinomas were multilocular cystic renal cell carcinoma (33%) and the pseudocystic necrotic carcinoma (31%), which usually belong to category IV. Less common cystic carcinomas were unilocular cystic renal cell carcinoma (6%) and renal cyst wall carcinoma (6%). The association of thin septa and large locules are suggestive findings for multilocular cystic nephroma, but such criteria are not specific enough to recognize benign multilocular cystic nephroma and to exclude multilocular cystic renal cell carcinoma. Since carcinomatous degeneration may occur within the wall of such tumors, especially in von Hippel Lindau disease, surgery is still required. The results of our study corroborate the Bosniak classification of cystic renal masses: no tumors belonged to the category I or II, all cystic masses which belonged to the category IV were malignant tumors, category III included benign and malignant tumors.