Xanthogranulomatous Pyelonephritis: Case Report.

BACKGROUND: In the emergency department (ED), pyelonephritis is a fairly common diagnosis, especially in patients with unilateral flank pain. Xanthogranulomatous pyelonephritis (XGP) is a rare type of pyelonephritis that is associated with unique features, which may lead to its diagnosis.

CASE REPORT: A 30-year-old male patient presented to the ED for evaluation of right-sided abdominal pain that has been ongoing for the past 24 hours. He noted the pain was located predominantly in the right flank and described it as sharp in nature. The pain was nonradiating and was associated with scant hematuria. He stated that he had similar pains approximately 1 month earlier that resolved after a few days. The patient underwent a bedside ultrasound and a subsequent computed tomography (CT) scan of the abdomen and pelvis, which showed an enlarged, multiloculated right kidney with dilated calyces and a large staghorn calculus, findings that represent XGP. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case report highlights an unusual variant of pyelonephritis, a relatively common ED diagnosis. XGP should be considered in patients with recurrent pyelonephritis, as treatment for XGP may require surgical intervention in addition to traditional antibiotic management.