This is kidney week! The cases will get progressively harder.
The CT scan shown above is from a 20 year old otherwise healthy woman presenting with flank pain, nausea, and vomiting. She does not have any urinary frequency, urgency, or pain. Her temperature is 38.1, and she has costovertebral angle tenderness. Pregnancy test is negative. A urinalysis is nitrite negative but shows WBCs and WBC casts in the urine.
Challenge: What's the diagnosis?
Image is shown under Fair Use.