Are there useful CT features to differentiate renal cell carcinoma from lipid-poor renal angiomyolipoma?

OBJECTIVE This study was an attempt to identify key CT features that can potentially be used to differentiate between lipid-poor renal angiomyolipoma and renal cell carcinoma (RCC). MATERIALS AND METHODS We conducted an analysis of patients who received nephrectomy or renal biopsy from 2002 to 2011 with suspected RCC. We included tumors smaller than 7 cm with a completed three-phase CT examination. A radiologist and a urology fellow, blinded to histopathologic diagnosis, recorded the imaging findings by consensus and compared the values for each parameter between lipid-poor angiomyolipoma, RCC subtypes, and RCC as a group. Multivariate logistic regression analysis was performed for each univariate significant feature. RESULTS The sample in our study consisted of 132 patients with 135 renal tumors, including 51 men (age range, 26-84 years; mean age, 57 years) and 81 women (age range, 29-91 years; mean age, 57 years). These tumors included 33 lipid-poor angiomyolipomas, 54 clear-cell RCC, 31 chromophobe RCC, and 17 papillary RCC. Multivariate analysis revealed four significant parameters for differentiating RCC as a group from lipid-poor angiomyolipoma (angular interface, p = 0.023; hypodense rim, p = 0.045; homogeneity, p = 0.005; unenhanced attenuation > 38.5 HU, p < 0.001), five for clear-cell RCC, two for chromophobe RCC, and one for papillary RCC. Lipid-poor angiomyolipoma and clear-cell RCC showed early strong enhancement and a washout pattern, whereas chromophobe RCC and papillary RCC showed gradual enhancement over time. CONCLUSION Specific CT features can potentially be used to differentiate lipid-poor renal angiomyolipoma from renal cell carcinoma.

[1]  Kyoung-Sik Cho,et al.  Differentiation of subtypes of renal cell carcinoma on helical CT scans. , 2002, AJR. American journal of roentgenology.

[2]  C. de Bazelaire,et al.  Hereditary renal cancer syndromes: an update of a systematic review. , 2010, European urology.

[3]  A. Megibow,et al.  CT diagnosis of renal angiomyolipoma: the importance of detecting small amounts of fat. , 1988, AJR. American journal of roentgenology.

[4]  A. Evans,et al.  Active surveillance of small renal masses: progression patterns of early stage kidney cancer. , 2011, European urology.

[5]  S. Silverman,et al.  Hyperattenuating renal masses: etiologies, pathogenesis, and imaging evaluation. , 2007, Radiographics : a review publication of the Radiological Society of North America, Inc.

[6]  E. Halpern,et al.  Renal manifestations of tuberous sclerosis complex: Incidence, prognosis, and predictive factors. , 2006, Kidney international.

[7]  Ahmed Mosbah,et al.  Differentiation of renal cell carcinoma subtypes by multislice computerized tomography. , 2005, The Journal of urology.

[8]  J. Milner,et al.  Fat poor renal angiomyolipoma: patient, computerized tomography and histological findings. , 2006, The Journal of urology.

[9]  N. Obuchowski,et al.  Enhancement characteristics of papillary renal neoplasms revealed on triphasic helical CT of the kidneys. , 2002, AJR. American journal of roentgenology.

[10]  Y. Ishikawa,et al.  Incidence of benign pathologic lesions at partial nephrectomy for presumed RCC renal masses: Japanese dual-center experience with 176 consecutive patients. , 2008, Urology.

[11]  M. Kattan,et al.  Incidence of benign lesions for clinically localized renal masses smaller than 7 cm in radiological diameter: influence of sex. , 2006, The Journal of urology.

[12]  O. Hélénon,et al.  Unusual fat-containing tumors of the kidney: a diagnostic dilemma. , 1997, Radiographics : a review publication of the Radiological Society of North America, Inc.

[13]  H. Shinmoto,et al.  Angiomyolipoma: imaging findings in lesions with minimal fat. , 1997, Radiology.

[14]  G. Sant,et al.  Computed tomographic findings in renal angiomyolipoma: an histologic correlation. , 1984, Urology.

[15]  D. Hartman,et al.  Angiomyolipoma: computed tomographic-pathologic correlation of 17 cases. , 1981, AJR. American journal of roentgenology.

[16]  N. Cho,et al.  Benign lesions after partial nephrectomy for presumed renal cell carcinoma in masses 4 cm or less: prevalence and predictors in Korean patients. , 2010, Urology.

[17]  K. Kihara,et al.  Diffusion‐weighted magnetic resonance imaging in the differentiation of angiomyolipoma with minimal fat from clear cell renal cell carcinoma , 2011, International journal of urology : official journal of the Japanese Urological Association.

[18]  F. Klein,et al.  Fat in renal cell carcinoma that lacks associated calcifications. , 2002, AJR. American journal of roentgenology.

[19]  J. Kaouk,et al.  Guideline for management of the clinical T1 renal mass. , 2009, The Journal of urology.

[20]  Prospective analysis of computerized tomography and needle biopsy with permanent sectioning to determine the nature of solid renal masses in adults. , 2003 .

[21]  Ming Zhou,et al.  Angiomyolipoma with minimal fat on MDCT: can counts of negative-attenuation pixels aid diagnosis? , 2009, AJR. American journal of roentgenology.

[22]  Christopher G. Roth,et al.  Exophytic renal masses: angular interface with renal parenchyma for distinguishing benign from malignant lesions at MR imaging. , 2010, Radiology.

[23]  Matthew S Davenport,et al.  Histogram analysis of small solid renal masses: differentiating minimal fat angiomyolipoma from renal cell carcinoma. , 2012, AJR. American journal of roentgenology.

[24]  L. Ngo,et al.  Angiomyolipoma with minimal fat: can it be differentiated from clear cell renal cell carcinoma by using standard MR techniques? , 2012, Radiology.

[25]  Namkug Kim,et al.  CT histogram analysis: differentiation of angiomyolipoma without visible fat from renal cell carcinoma at CT imaging. , 2008, Radiology.

[26]  Matthew S Davenport,et al.  Diagnosis of renal angiomyolipoma with hounsfield unit thresholds: effect of size of region of interest and nephrographic phase imaging. , 2011, Radiology.

[27]  Jeong Kon Kim,et al.  Angiomyolipoma with minimal fat: differentiation from renal cell carcinoma at biphasic helical CT. , 2004, Radiology.

[28]  M. Jinzaki,et al.  Double-Phase Helical CT of Small Renal Parenchymal Neoplasms: Correlation with Pathologic Findings and Tumor Angiogenesis , 2000, Journal of computer assisted tomography.

[29]  M. Singh,et al.  Renal cell carcinoma containing fat mimicking angiomyolipoma: demonstration with CT scan and histopathology , 1998, European Radiology.

[30]  Chaya S Moskowitz,et al.  Solid renal cortical tumors: differentiation with CT. , 2007, Radiology.

[31]  Jeong Kon Kim,et al.  Renal angiomyolipoma with minimal fat: differentiation from other neoplasms at double-echo chemical shift FLASH MR imaging. , 2006, Radiology.

[32]  S. Herrell,et al.  Second prize: frequency of benign renal cortical tumors and histologic subtypes based on size in a contemporary series: what to tell our patients. , 2007, Journal of endourology.

[33]  Anthony E. Samir,et al.  Pixel distribution analysis: can it be used to distinguish clear cell carcinomas from angiomyolipomas with minimal fat? , 2008, Radiology.

[34]  P. Taourel,et al.  Characterization of small solid renal lesions: can benign and malignant tumors be differentiated with CT? , 2011, AJR. American journal of roentgenology.

[35]  Erick M Remer,et al.  Clinical correlates of renal angiomyolipoma subtypes in 209 patients: classic, fat poor, tuberous sclerosis associated and epithelioid. , 2008, The Journal of urology.