Xanthogranulomatous Pyelonephritis Causing Renocolic Fistula Presenting as Symptomatic Anemia.

Renocolic fistula is a rare clinical finding that is most commonly iatrogenic after surgical intervention. Herein, we present a case of renocolic fistula secondary to xanthogranulomatous pyelonephritis (XGP) with a subtle presentation as anemia. A 40-year-old female was found to have a hemoglobin of 6.5 g/dL after presenting for worsening fatigue. A urinalysis was remarkable for numerous white blood cell (WBC), positive bacteria, and nitrite. As part of her anemia workup, an esophagogastroduodenoscopy (EGD) was done which was normal while a colonoscopy showed a fistula opening with surrounding nodularity close to the splenic flexure of the colon. A computed tomography (CT) scan of the abdomen and pelvis with contrast showed chronic left kidney pyelonephritis with multiple contiguous abscesses in the inferior left kidney in addition to a staghorn calculus concerning for XGP. The patient was started on antibiotics and underwent laparotomy with repair of the renocolic fistula, partial omentectomy, and left nephrectomy. She tolerated the surgery well and was discharged with a stable hemoglobin. 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 treatment.