Case Presentation: MG is an 18 year old male with quadriplegia from c-spine injury and chronic respiratory failure with trach/vent dependence who presented with 2-3 weeks of intermittent fevers, chills, malaise, abdominal pain, nausea, emesis, diarrhea, and anorexia. Initial evaluation revealed leukocytosis, thrombocytosis, and mild anemia. Urinalysis was significant for moderate leukocyte esterase, nitrites, pyuria, and bacteriuria. MG was admitted on IV antibiotics for presumed acute pyelonephritis, with urine culture later growing E.coli and Klebsiella. Abdominal XR and ultrasound showed left renal calculi and asymmetric renal enlargement. CT imaging further revealed a large obstructing stone in the left ureter with heterogenous delayed enhancement, multiple intraparenchymal and hilar foci of nonenhancement, and superimposed dilation of the renal pelvis/calyces containing multiple stones. All these findings together were concerning for the diagnosis of xanthogranulomatous pyelonephritis. Initially, a percutaneous nephrostomy tube was placed, however the severity of disease left a nonviable kidney, and a complete excision was required to mitigate infection risk.

Discussion: Xanthogranulomatous Pyelonephritis (XGP) is a rare and aggressive form of chronic pyelonephritis usually resulting from chronic obstructing nephrolithiasis and leading to a non-functional kidney. Its exact pathway is unknown, but it is thought chronic inflammation causes destruction of renal and peri-renal tissue which is then replaced with granulomatous tissue containing lipid-laden macrophages. Its incidence is estimated between 0.6%-1% of all recurrent kidney infections and most commonly occurs in the 5th-6th decade of life with female predominance. As uncommon as XGP is, it is even more rare in children who are typically diagnosed by age 10 (mean age 5 years). Case reports in children show typical pyelonephritis symptoms with additional features of renal mass, hydronephrosis, anemia, and hematuria. In MG, key diagnostic features such as flank pain and dysuria were absent due to his quadriplegia and likely led to his atypical presentation. Notably, MG began having recurrent UTIs only after he developed a neurogenic bladder from his injury and continued to have recurrent UTIs when not prophylactically treated.

Conclusions: XGP is an aggressive form of chronic pyelonephritis that results from chronic obstructing nephrolithiasis. It is rare in the general population, exceedingly rare in children, and essentially nonexistent per our literature search in our patient’s age group. Still, it should be on the differential for anyone who presents with an abdominal mass, flank pain, or hematuria, concurrent with fever or other signs of infection, especially in patients with recurrent UTIs. More research needs to be done on the prevalence of XGP, with special consideration for risk factors in medically complex patients and those that do not experience localized symptoms of UTI such as MG.