Entero-Appendiceal Fistula Presenting with Overt Gastrointestinal Bleeding: A Case Report

Entero-appendiceal fistula is an extremely rare entity, with very few cases reported in the literature. Most previously described cases presented with abdominal pain or were diagnosed incidentally. To our knowledge, there have been no reports of such a fistula presenting with overt gastrointestinal bleeding.

A 56-year-old man with a medical history of human immunodeficiency virus infection, alcoholic cirrhosis, and paroxysmal atrial fibrillation, who was under regular follow-up at our hospital, presented with a 4-day history of hematochezia that was occurring 3-4 times per day. He was found to have severe anemia with a hemoglobin level of 6.6 g/dL and was emergently hospitalized on the same day. Contrast-enhanced CT did not reveal active extravasation. Colonoscopy showed multiple diverticula but no clear bleeding source. Recurrent hematochezia prompted repeat imaging, and subsequent CT showed extravasation in the ileum. Colonoscopy again revealed blood originating from a segment proximal to the reach of the colonoscope, suggesting bleeding from a more proximal segment. Double-balloon enteroscopy revealed a hemorrhagic submucosal tumor-like lesion located approximately 100 cm proximal to the ileocecal valve. Biopsy was inconclusive, but surgical resection was indicated because of the ongoing bleeding and the need to exclude malignancy. Laparoscopic resection revealed that the tip of the appendix had formed a fistula into the ileal lumen. Histopathological examination confirmed a full-thickness fistula between the appendix and ileum, with no evidence of malignancy.

This is the first reported case of an entero-appendiceal fistula presenting with overt gastrointestinal bleeding and endoscopic features mimicking a submucosal tumor. Although extremely rare, this condition should be considered in the differential diagnosis of small intestinal tumors, particularly in patients with a history of complicated appendicitis or immunosuppression.