Renal cancer is frequent and its diagnosis mainly dependant on imaging. More than 50% of 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 fine needle aspiration (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.