Xanthogranulomatous pyelonephritis is a rare type of pyelonephritis associated with chronic and/or recurrent bacterial infections. Its diagnosis can be challenging, especially if it is not considered in the differential diagnosis of a renal mass.


It is usually seen in an older adult female but can present at any age.


Clinical features of xanthomatous pyelonephritis:

(1) palpable renal or flank mass

(2) hematuria

(3) intermittent fevers

(4) history of recurrent urinary tract infection and/or nephrolithiasis

(5) abdominal or lumbar pain

(6) anorexia with weight loss


Laboratory features:

(1) anemia

(2) elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP)


Differential diagnosis:

(1) renal tumor

(2) perinephric abscess


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