What is the salient abnormality in the case?
Bilateral subcapsular collections surrounding both kidneys.
What could be the most likely cause for such abnormality?
Such fluid attenuation collections could be due to trauma or cyst rupture, however this rare appearance (fluid attenuation subcapsular collections, and bilaterality) is more characteristic of renal lymphangiectasia.
Three-phase renal CT demonstrates enlarged, low attenuating kidneys. When contrast is administered, sub-capsular fluid can be identified along with a number of peripelvic cysts.
Swollen kidneys but no hydronephrosis or any calculi in the urinary tract.
On the renal parenchymal phase there is bilateral symmetrical subcapsular fluid collections with poor enhancement of renal parencyma (worse on the left). As well as symmetrical subcapsular fluid collections with poor renal parencymal contrast enhancement
On the excretory phase, there is excretion of contrast bilaterally but slower on the left with mild dilatation of renal pelvis.
The previous study showing the same subcapsular fluid collections but more normal contrast excretion. Note thickening of the upper left ureter with resultant luminal narrowing