Sonography of renal sinus lipomatosis

This middle aged patient presented with non specific complaints and we did a routine abdominal ultrasonography on him. This is what we found on ultrasound imaging of the kidneys:

Both kidneys showed echogenic matter within the region of the renal sinuses- and this was more prominent in the left kidney. The large echogenic mass like appearance in the lower part of the left renal sinus prompted us to think that this could be angiomyolipoma, one of the more common entities in the kidney. However, further imaging showed that this hyperechoic deposit was almost totally within the confines of the renal sinuses. Besides the lesions were bilateral.
 See ultrasound video clips below:

 

Further observe the vessels within the renal sinus of the left kidney in this color Doppler ultrasound video clip below:

 

The most obvious diagnosis based on these ultrasound images and video clips is renal sinus lipomatosis.

The uniformly homogenous appearance of the fatty tissue in the renal sinus suggests lipomatosis rather than any more ominous masses/ malignancies of the renal sinus. These ultrasound findings are suggestive of a grade -1 renal sinus lipomatosis of both kidneys.

References: http://www.jultrasoundmed.org/cgi/reprint/21/9/993 (free excellent article with images)

For more ultrasound/ color Doppler images of this case see:

http://www.ultrasound-images.com/kidneys.htm#Renal_sinus_lipomatosis