Chronic Diarrhea as the Only Symptom in a Patient With Duodenal-Colo-Renal Primary Fistula

A 91-year-old woman presented to our center complaining of nonbloody diarrhea for 6 months and an associated 10-kg weight loss. Her initial lab results suggested hypochromic microcytic anemia. Upper endoscopy showed a fistula between the second portion of duodenum and the right colon (Figure 1). Through the fistula tract, a solid viscera with a nodular mucosa was visible in the lumen of the right colon (Figure 2). Abdominal computed tomography revealed a mass between the right colon, the second portion of duodenum, and the right kidney; this allowed the passage of oral contrast between these structures, confirming that the solid viscera seen on endoscopy was in fact the right kidney (Figure 3). Histology of the biopsied viscera confirmed a poorly differentiated renal carcinoma. Given the stage of her disease, age, and comorbidities, the patient was referred for palliative management; 2 months later, the patient died