Xanthogranulomatous Pyelonephritis in a Transplant Kidney Leading to Severe Allograft Dysfunction.

Xanthogranulomatous pyelonephritis (XPN) is a rare and unusual form of pyelonephritis that infrequently occurs in renal allografts. Clinical presentation ranges from asymptomatic to fever, pyuria, and graft dysfunction. We present a case of a young African American male who presented with a marked elevation in serum creatinine from a baseline of 1.8-1.9 to 9.86 mg/dL. Transplant kidney biopsy was consistent with the diagnosis of XPN, showing xanthoma cells, which are pathognomonic for this condition. Following antibiotic treatment, allograft function improved and return to dialysis was averted. Clinicians should consider XPN in transplant patients with deteriorating allograft function, as its presentation can mimic more common conditions. Graft salvage with appropriate antimicrobial therapy should be attempted before considering nephrectomy which risks reinitiation of dialysis.