Chronic granulomatous interstitial nephritis: unusual complication of acute pyelonephritis.

We describe an unusual complication of acute pyelonephritis in a 45-year-old diabetic female. She was admitted to our hospital due to fever and flank pain which had developed 10 days earlier. Urinalysis showed many WBC and urine culture revealed Escherichia coli. After adequate antibiotic treatment, clinical symptoms abated but renal failure and leukocyturia persisted. Abdominal CT showed bilateral focal bacterial nephritis and renal biopsy disclosed chronic granulomatous interstitial nephritis. On the 80th hospital day she was discharged with a serum creatinine of 299 mumol/l. In the outpatient clinic, renal dysfunction and leukocyturia persisted up to 1 year. In conclusion, this case raises the possibility of a chronic interstitial process of acute pyelonephritis.