Xanthogranulomatous Pyelonephritis Causing a Renocolic Fistula Presenting as Symptomatic Anemia

Abstract

Renocolic fistula is a rare clinical finding that is most commonly iatrogenic after surgical intervention. Herein, we present a case of spontaneous renocolic fistula secondary to Xanthogranulomatous pyelonephritis (XGP) with a subtle presentation as anemia. Given the subtle presentation in our case, colonoscopy findings were the trigger for further investigations.: This is a 40-year-old female was asked to go to the ED by her primary care physician (PCP) for low hemoglobin on routine labs. Patient had been complaining of fatigue, nausea, diarrhea, dysuria and urinary frequency for 7 days. Labs in the Emergency departement (ED) were remarkable for a hemoglobin of 6.5 g/dL (down from 10 g/dL 3 months prior) white blood cell count (WBC) of 18x103 cmm, creatinine of 1.87 mg/dL (baseline is 1 mg/dL) with blood urea nitrogen (BUN) of 24 mg/dL. Urinalysis was remarkable for too numerous WBC, positive bacteria and nitrite. Patient received 1 Unit of packed red blood cells and was started on Ceftriaxone for a urinary tract infection. No overt source of bleeding was identified. An esophagogastroduodenoscopy (EGD) was normal while colonoscopy showed a fistula with surrounding nodularity close to the splenic flexure of the colon (figure 1), a small amount of pus was also noted coming out from the fistula. Shortly after, the patient spiked a fever of 102.7F. C-Reactive protein (CRP) and Erythrocyte sedimentation rate (ESR) were both elevated at 17 and 140 respectively which raised the concern of inflammatory bowel disease. A CT scan of the abdomen and pelvis with contrast showed findings of acute on chronic left kidney pyelonephritis with multiple contiguous abscesses in the inferior left kidney with a staghorn calculus concerning for XGP, it also showed the fistula between the left kidney and the splenic flexure of the colon (Figure 2,3). The patient underwent exploratory laparotomy, takedown and repair of renocolic fistula, partial omentectomy and left nephrectomy by urology and general surgery teams. Patient had an uncomplicated post-operative course and was discharged home on post-operative day 6 with a stable hemoglobin of 8 g/dL.1521_B Figure 2. CT scan of the abdomen and pelvis showing a renocolic fistula and xanthogranulomatous pyelonephritis1521_C Figure 3. CT scan of the abdomen and pelvis showing a renocolic fistula and xanthogranulomatous pyelonephritisIn conclusion, XGP is a rare type of chronic pyelonephritis that is usually a result of chronic obstruction by an infected stone. Spontaneous renocolic fistulas are rare nowadays with the advancement in antibiotics and renal stones management.1521_A Figure 1. Colonoscopy showing a fistula opening with surrounding nodularity