Watch Where You Are Going!: A Case of a Malignant Coloduodenal Fistula

The patient is an 83 year old female with past medical history of hypertension, atrial fibrillation and hyperlipidemia who presented to her primary care with symptoms of abdominal distension and diarrhea. During her diagnostic work up, she had cross sectional imaging of the abdomen which demonstrated a mass within the transverse colon. An inpatient colonoscopy was scheduled to evaluate for colorectal malignancy. During the colonoscopy, a large, malignant, partially obstructing neoplasm was noted in the transverse colon. Attempts were made to endoscopically traverse the mass. During those attempts, rugal folds were noted by the endoscopist who realized that he had passed the colonoscopy within the lumen of the stomach. There was a fistulous tract connecting the duodenal bulb with this transverse colon mass. The patient was then evaluated by the surgical oncology service and had a successful surgical gastrojejunostomy. Colo-duodenal fistulas are uncommon and can be separated into both benign and malignant causes. Malignant causes include colorectal cancer, carcinoma of the gallbladder, small bowel, or esophagus. Benign causes can include Crohn's disease, cholelithiasis and ruptured pancreatic pseudocysts. Diagnosis is typically made radiologically using a contrast enhanced study such as an Upper GI series or a CT scan. It is uncommon to make this diagnosis of colo duodenal fistula endoscopically. However, we were able to make such a diagnosis by pure coincidence.