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Imaging findings of common benign renal tumors in the era of small renal masses: differential diagnosis from small renal cell carcinoma: current status and future perspectives.

Woo S, Cho JY - Korean J Radiol (2015)

Bottom Line: The prevalence of small renal masses (SRM) has risen, paralleling the increased usage of cross-sectional imaging.Therefore, differentiation between early renal cell carcinoma (RCC) and benign SRM is critical to achieve proper management.Furthermore, the role of percutaneous biopsy is discussed as imaging is yet imperfect, therefore necessitating biopsy in certain circumstances to confirm the benignity of SRMs.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.

ABSTRACT
The prevalence of small renal masses (SRM) has risen, paralleling the increased usage of cross-sectional imaging. A large proportion of these SRMs are not malignant, and do not require invasive treatment such as nephrectomy. Therefore, differentiation between early renal cell carcinoma (RCC) and benign SRM is critical to achieve proper management. This article reviews the radiological features of benign SRMs, with focus on two of the most common benign entities, angiomyolipoma and oncocytoma, in terms of their common imaging findings and differential features from RCC. Furthermore, the role of percutaneous biopsy is discussed as imaging is yet imperfect, therefore necessitating biopsy in certain circumstances to confirm the benignity of SRMs.

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Related in: MedlinePlus

Comparison of relative echogenicity between small renal cell carcinoma (RCC) and angiomyolipoma (AML) with minimal fat.A. Mass (arrow) in right kidney lower pole in 43-year-old woman shows high echogenicity but less than that of sinus fat. Relative echogenicity ([echogenicity of mass - echogenicity of renal cortex] / [echogenicity of sinus fat - echogenicity of renal cortex]) was calculated as 0.63. Upon surgery, mass was confirmed as clear cell RCC. B. Mass (arrow) in left kidney interpolar in 38-year-old woman shows high echogenicity, even higher than that of sinus fat. Relative echogenicity was measured as 2.10. Mass was confirmed as AML with minimal fat at surgery.
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Figure 1: Comparison of relative echogenicity between small renal cell carcinoma (RCC) and angiomyolipoma (AML) with minimal fat.A. Mass (arrow) in right kidney lower pole in 43-year-old woman shows high echogenicity but less than that of sinus fat. Relative echogenicity ([echogenicity of mass - echogenicity of renal cortex] / [echogenicity of sinus fat - echogenicity of renal cortex]) was calculated as 0.63. Upon surgery, mass was confirmed as clear cell RCC. B. Mass (arrow) in left kidney interpolar in 38-year-old woman shows high echogenicity, even higher than that of sinus fat. Relative echogenicity was measured as 2.10. Mass was confirmed as AML with minimal fat at surgery.

Mentions: Traditionally, a hyperechoic renal mass on US without features of a hypoechoic rim or intratumoral cysts is considered typical for AML when compared with RCC (12). However, when it comes to small AML with minimal fat, there has been some controversy over the echogenicity of AMLs. Some have reported that they are homogeneously isoechoic (20, 21), whereas others found that they are hyperechoic (19) or only slightly hyperechoic (22). Most of these studies comparing the echogenicity of RCC and AML with minimal fat have been done on a subjective basis and are not dedicated studies of SRMs. On the other hand, Lee et al. (23) reported that measuring the relative echogenicity of the lesion at a picture archiving and communication system monitor with the renal cortex and sinus fat referenced as 0 and 100%, respectively, was useful in differentiating small AMLs from RCCs. While small AML with minimal fat (88%) demonstrated lesser relative echogenicity than classic AML (106.3%), it showed greater relative echogenicity compared with all subtypes (44.1%) of RCC (Fig. 1). Although, further validation may be needed, in our experience, we believe that comparing the relative echogenicity with that of sinus fat can be helpful in clinical practice.


Imaging findings of common benign renal tumors in the era of small renal masses: differential diagnosis from small renal cell carcinoma: current status and future perspectives.

Woo S, Cho JY - Korean J Radiol (2015)

Comparison of relative echogenicity between small renal cell carcinoma (RCC) and angiomyolipoma (AML) with minimal fat.A. Mass (arrow) in right kidney lower pole in 43-year-old woman shows high echogenicity but less than that of sinus fat. Relative echogenicity ([echogenicity of mass - echogenicity of renal cortex] / [echogenicity of sinus fat - echogenicity of renal cortex]) was calculated as 0.63. Upon surgery, mass was confirmed as clear cell RCC. B. Mass (arrow) in left kidney interpolar in 38-year-old woman shows high echogenicity, even higher than that of sinus fat. Relative echogenicity was measured as 2.10. Mass was confirmed as AML with minimal fat at surgery.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4296282&req=5

Figure 1: Comparison of relative echogenicity between small renal cell carcinoma (RCC) and angiomyolipoma (AML) with minimal fat.A. Mass (arrow) in right kidney lower pole in 43-year-old woman shows high echogenicity but less than that of sinus fat. Relative echogenicity ([echogenicity of mass - echogenicity of renal cortex] / [echogenicity of sinus fat - echogenicity of renal cortex]) was calculated as 0.63. Upon surgery, mass was confirmed as clear cell RCC. B. Mass (arrow) in left kidney interpolar in 38-year-old woman shows high echogenicity, even higher than that of sinus fat. Relative echogenicity was measured as 2.10. Mass was confirmed as AML with minimal fat at surgery.
Mentions: Traditionally, a hyperechoic renal mass on US without features of a hypoechoic rim or intratumoral cysts is considered typical for AML when compared with RCC (12). However, when it comes to small AML with minimal fat, there has been some controversy over the echogenicity of AMLs. Some have reported that they are homogeneously isoechoic (20, 21), whereas others found that they are hyperechoic (19) or only slightly hyperechoic (22). Most of these studies comparing the echogenicity of RCC and AML with minimal fat have been done on a subjective basis and are not dedicated studies of SRMs. On the other hand, Lee et al. (23) reported that measuring the relative echogenicity of the lesion at a picture archiving and communication system monitor with the renal cortex and sinus fat referenced as 0 and 100%, respectively, was useful in differentiating small AMLs from RCCs. While small AML with minimal fat (88%) demonstrated lesser relative echogenicity than classic AML (106.3%), it showed greater relative echogenicity compared with all subtypes (44.1%) of RCC (Fig. 1). Although, further validation may be needed, in our experience, we believe that comparing the relative echogenicity with that of sinus fat can be helpful in clinical practice.

Bottom Line: The prevalence of small renal masses (SRM) has risen, paralleling the increased usage of cross-sectional imaging.Therefore, differentiation between early renal cell carcinoma (RCC) and benign SRM is critical to achieve proper management.Furthermore, the role of percutaneous biopsy is discussed as imaging is yet imperfect, therefore necessitating biopsy in certain circumstances to confirm the benignity of SRMs.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea.

ABSTRACT
The prevalence of small renal masses (SRM) has risen, paralleling the increased usage of cross-sectional imaging. A large proportion of these SRMs are not malignant, and do not require invasive treatment such as nephrectomy. Therefore, differentiation between early renal cell carcinoma (RCC) and benign SRM is critical to achieve proper management. This article reviews the radiological features of benign SRMs, with focus on two of the most common benign entities, angiomyolipoma and oncocytoma, in terms of their common imaging findings and differential features from RCC. Furthermore, the role of percutaneous biopsy is discussed as imaging is yet imperfect, therefore necessitating biopsy in certain circumstances to confirm the benignity of SRMs.

Show MeSH
Related in: MedlinePlus