In the paper “Differentiation of oncocytoma and renal cell carcinoma in small renal masses ( <4 cm ): the role of 4-phase computerized tomography” published online August 18, 2010, in World Journal of Urology, Bird V.G. and colleagues [1] write in the Discussion: “With the advancement of imaging techniques, enhancement patterns of renal tumors on CT have evolved to be the best, though limited, non-invasive technique to predict the pathological diagnosis of renal tumors. Implementing this technique to differentiate oncocytoma from the subtypes of RCC will have a great impact on the management of patients. In conclusion, non-invasive differentiation between benign and malignant renal tumors has paramount importance in determining the management plan for patients.”We do not agree with these statements. The small renal masses (SRMs) may be defined as neoplastic lesions <4 cm in diameter, which are more and more often found, especially in elderly and comorbid patients. Today, the vast majority of SRMs are incidentally diagnosed and therefore tend to have a better prognosis [2–4]. Nephron-sparing surgery (NSS) is the standard care for SRMs (stage pT1a). Patients with SRMs who are treated with NSS exhibit similar recurrence-free (0–3%) and 5-year cancer-specific survival when compared with renal nefrectomy [5–9]. SRMs include malignant and benign tumors. In the urologic practice, all SRMs should be removed with NSS independently from their histological nature. We believe that the differentiation of oncocytoma and renal cell carcinoma in SRMs is unnecessary because the tumor should be removed with NSS independently of its histological nature. Non-invasive differentiation between benign and malignant renal tumors has paramount importance in determining the management plan for patients only when the tumor is >4 cm in diameter.