Renal Cell Carcinomas: Sonographic Appearance Depending on Size and Histologic Type

Area of Science:

• Radiology
• Oncology
• Pathology

Background:

• Malignant renal cell carcinomas (RCC) can exhibit echogenicity similar to benign angiomyolipomas (AML) on ultrasound.
• Previous findings suggested small echogenic renal masses are typically benign.
• This study aimed to re-evaluate the sonographic appearance of RCC, specifically focusing on hyperechoic presentations.

Purpose of the Study:

• To confirm that some renal cell carcinomas can present as hyperechoic masses on sonography.
• To investigate the characteristics of hyperechoic renal cell carcinomas.

Main Methods:

• Retrospective review of 91 pathologically proven renal cell carcinoma cases with corresponding sonography.
• Histologic subtyping (clear cell, papillary, chromophobe) and size stratification (<3 cm, 3 cm or larger).
• Tumor echogenicity graded on a 5-point scale relative to renal parenchyma.

Main Results:

• 51% of tumors were 3 cm or smaller; most were isoechoic (35%) or mildly hyperechoic (26%).
• Tumors <2 cm were often mildly hyperechoic (29%) or very hyperechoic (29%).
• Tumors >3 cm were predominantly isoechoic (49%) or mildly hyperechoic (33%), with only 4% very hyperechoic.

Conclusions:

• A subset of renal cell carcinomas exhibit very hyperechoic sonographic appearances.
• These hyperechoic RCCs may be misdiagnosed as benign entities like angiomyolipomas.
• Sonographic echogenicity alone is insufficient to rule out malignancy in renal masses.