This is a spectrum of severe pyelonephritis with obstructive proximal ureteric stone, complicated by a large abscess formation. It does not have typical features of XGP (cortical thinning, diffuse enlargement), but that is not worth getting caught up on - what is most important to remember here is that an infected, obstructed kidney needs urgent attention for decompression due to risk of sepsis, loss of kidney and death (i.e. call IR to evaluate for percutaneous nephrostomy tube placement).