ABSTRACT Purpose: To determine whether benign exophytic renal masses can be distinguished from malignant lesions by using the angular interface sign in ultrasonography (US) and computerized tomography (CT). Materials and Methods: A total of 71 cases with exophytic renal mass (2 cm or greater) were examined on the basis of angular interface in US (n = 23), CT (n = 21) and US + CT (n = 16) between January 2008 and June 2010 were included in this study. The renal interface relationships were examined by 2 radiologists and classified as having angular or wide interface. Results: No statistically significant difference was found between the findings of two readers. There was almost perfect interobserver agreement for the interface sign. For cystic lesions, the angular interface sign was determined in all but two Bosniak category 1 cases. Also, the angular interface sign was positive in all but one Bosniak category 2 - 3. For cystic lesions with solid component and pure solid lesions, in the benign group, the angular interface sign was positive in all except three cases (vascular malformation, oncocytoma and Xanthogranulomatous pyelonephritis). In the malignant group, the angular interface sign was determined in only two RCC cases; in other primary or metastatic malignant lesions there was a wide interface sign. Conclusion: Exophytic renal masses can be differentiated as malignant or benign with 87% accuracy using only the angular interface sign in US or CT and also in opposition to dynamic-contrast examinations. This method entails a lack of additional radiation or contrast media exposure, time-saving, and costeffectivity.
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D. Yildirim, H. Bozkurt, A. Cirakoglu, M. Sahin, B. Gurses and B. Ekci, "Differentiation of Exophytic Renal Masses with Determination of the Angular Interface with Renal Parenchyma in US and CT," Open Journal of Medical Imaging, Vol. 2 No. 2, 2012, pp. 80-83. doi: 10.4236/ojmi.2012.22014.
 J. B. Zhang, R. A. Lefkowitz, N. M. Ishill, L. Wang, C. S. Moskowitz, P. Russo, H. Eisenberg and H. Hricak, “Solid Renal Cortical Tumors: Differentiation with CT,” Radiology, Vol. 244, No. 2, 2007, pp. 494-504.
 G. M. Israel, N. Hindman and M. A. Bosniak, “Evaluation of Cystic Renal Masses: Comparison of CT and MR Imaging by Using the Bosniak Classification System,” Radiology, Vol. 231, No. 2, 2004, pp. 365-371.
 O. Hélénon, J. Correas, C. Balleyguier, M. Ghouadni and F. Cornud, “Ultrasound of Renal Tumors,” European Radiology, Vol. 11, No. 10, 2001, pp. 1890-1901.
 S. R. Prasad, N. C. Dalrymple and V. R. Surabhi, “CrossSectional Imaging Evaluation of Renal Masses,” Radiologic Clinics of North American, Vol. 46, No. 1, 2008, pp. 95-111. doi:10.1016/j.rcl.2008.01.008
 G. M. Israel and M. A. Bosniak, “MR Imaging of Cystic Renal Masses,” Magnetic Resonance Imaging Clinics of North America, Vol. 12, No. 3, 2004, pp. 403-412.
 S. K. Verma, D. G. Mitchell, R. Yang, C. G. Roth, P. O’Kane, M. Verma and L. Parker, “Exophytic Renal Masses: Angular Interface with Renal Parenchyma for Distinguishing Benign from Malignant Lesions at MR Imaging,” Radiology, Vol. 255, No. 2, 2010, pp. 501-507.
 C. L. Siegel, E. G. McFarland, J. A. Brink, A. J. Fisher, P. Humphrey and J. P. Heiken, “CT of Cystic Renal Masses: Analysis of Diagnostic Performance and Interobserver Variation,” American Journal of Roentgenology, Vol. 169, No. 3, 1997, pp. 813-818.
 E. K. Outwater, M. Bhatia, E. S. Siegelman, M. A. Burke and D. G. Mitchell, “Lipid in Renal Clear Cell Carcinoma: Detection on Opposed-Phase Gradient-Echo MR Images,” Radiology, Vol. 205, No. 1, 1997, pp. 103-107.
 J. K. Kim, T. K. Kim, H. J. Ahn, C. S. Kim, K. R. Kim and K. S. Cho, “Differentiation of Subtypes of Renal Cell Carcinoma on Helical CT Scans,” American Journal of Roentgenology, Vol. 178, No. 6, 2002, pp. 1499-1506.
 W. Siu, K. S. Hafez, W. K. Johnston III and J. S. Wolf Jr., “Growth Rates of Renal Cell Carcinoma and Oncocytoma under Surveillance are Similar,” Urologic Oncology, Vol. 25, No. 2, 2007, pp. 115-119.
 S. K. Morcos, H. S. Thomsen, J. A. W. Webb and members of the Contrast Media Safety Committee of the European Society of Urogenital Radiology (ESUR), “Contrast-Media-Induced Nephrotoxicity: A Consensus Report,” European Radiology, Vol. 9, No. 8, 1999, pp. 1602-1613. doi:10.1007/s003300050894