Cystic renal tumors in adults: radiologic-pathologic correlations

The purpose of this study is to provide an updated pathologic-radiologic cl assification of cystic renal tumors and to assess imaging diagostic capabil ities. Eighty seven cases of cystic renal tumors explored with multimodalit y imaging (ultrasonography, CT, MRI, arteriography) and with histopathologi c correlation are reported. The most common cystic carcinomas were multiloc ular cystic renal cell carcinoma (33 %) and the pseudocystic necrotic carci noma (31 %), which usually belong to category IV. Less common cystic carcin omas were unilocular cystic renal cell carcinoma (6 %) and renal cyst wall carcinoma (6 %). The association of thin septa and large locules are sugges tive findings for multilocular cystic nephroma, but such criteria are not s pecific enough to recognize benign multilocular cystic nephroma and to excl ude multilocular cystic renal cell carcinoma. Since carcinomatous degenerat ion may occur within the wall of such tumors, especially in von Hippel Lind au disease, surgery is still recquired. The results of our study corroborat e 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 w ere malignant tumors, category III included benign and malignant tumors.