The Importance of Benign Kidney Tumors Among Small Renal Masses: Diagnosis and Treatment Algorithms/Kucuk Boyutlu Bobrek Kitlelerinde Iyi Huylu Tumorlerin Onemi: Tani Ve Tedavi Algoritmleri (Report‪)‬

Incidence of small renal tumors Understanding the biologic behavior and natural history of small renal masses is crucial in predicting tumor growth and metastatic potential, so as to properly select the methods and optimal timing of intervention. [1] Since the wide-spread introduction of cross-sectional imaging modalities such as ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI), the detection rate of renal tumors have increased. The majority of these solid renal tumors (SRTs) are actually small SRTs [less than or equal to] 4 cm in diameter. [2,3] Today the majority (60%) of renal tumors are found incidentally in asymptomatic patients. In their study over a 20-year period, Hollingsworth et al. [4] reported an increase of 285% and 244%, in the incidence of SRT 2 cm and 2-4 cm, respectively. However, the underlying biology of the lesion, benign or malign, was still unknown. [5,6] It is generally believed that most renal tumors are renal cell carcinomas (RCCs). Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Several benign tumors show characteristic imaging features, like typical angiomyolipomas (AMLs). However, because of overlapping of findings between benign and malignant renal tumors, histological evaluation is required to establish a definitive diagnosis in most cases. Accurate preoperative characterization facilitates optimal patient management. In a study from the Mayo clinic, Frank et al. [7], retrospectively examined 2935 SRTs of all sizes treated over a 25-year period and reported 46.3%, 22.4%, 22.0%, and 19.9% of renal lesions 1 cm, 2 cm, 3 cm, and 4 cm in size, respectively, to be benign. In a recent report by Remzi et al. [8], SRTs 2 cm, 2-3 cm, and 3-4 cm in size were reported to be benign in 24.6%, 20.4%, and 16.0% of cases, respectively (p=0.66). Thus, tumor size alone was not able to provide adequate information for a treatment decision. The crucial issue before a treatment decision should be the determination of the exact nature of an incidentally discovered mass, because SRTs show heterogeneous pathologic features ranging from totally benign to highly aggressive.