The histopathological diagnosis was considered the gold standard. Histopathology diagnosis was available for all tumors after percutaneous biopsy samples were obtained using an 18-gauge semiautomatic side-cutting needle (SemiCut, MDL, Delebio, Italy). At least two samples of each tumor were obtained and analyzed according to the World Health Organization guidelines by a pathologist with more than 4 years of specialized experience in diagnosing renal tumors.