Renal cancer is frequent and its diagnosis mainly dependant on imaging. More than 50% renal tumors are currently diagnosed without symptoms. However, 20% of small solid tumors are benign and this percentage is much higher in atypical cystic tumors Bosniak II and III, where 76% and 59% are benign respectively. Determining the malignancy by imaging in these cases is difficult and sometimes impossible. The FNA cytology or biopsy is necessary. The diagnostic sensitivity and specificity with biopsy are high, but the potential tumor contamination is a major risk. The FNA cytology is simple and safe, but its sensitivity is about 50%. We are conducting a multicentric prospective study to add the molecular markers in FNA cytology as a new diagnostic method in imaging-indeterminate renal tumors.

Four molecular markers including MN/CA9, vimentin, KIT and S100A1 will be studied. These four markers have been reported to have a differential diagnostic value in renal tumors. MN/CA9 and vimentin are often found in conventional renal cancers. KIT is frequently expressed in renal oncocytomas and chromophobe renal cancers. S100A1 may further distinguish renal oncocytoma from chromophobe renal cancer. These markers will be analyzed by RT-PCR.

The aim of this study is to evaluate the diagnostic performance of the association cytology-molecular markers in imaging-indeterminate renal tumors (small solid tumors and cystic tumors ≥ Bosniak III). About 156 patients will be included. in five french clinical centers including Saint-Etienne, Marseille, Grenoble, Toulouse and Nancy.

The expected results will improve the preoperative diagnostic accuracy in renal tumors.