Pancreaticocolonic fistulae: a rare cause of profound diarrhoea

A woman in her 60s developed diarrhoea after receiving amoxicillin/clavulanic acid for biliary pancreatitis. After a diagnosis of Clostridioides difficile infection, she was treated with fidaxomicin. Despite initial improvement, her diarrhoea recurred, with increased severity, and repeated testing for C. difficile was negative. Further diagnostic workup yielded negative results for infectious, autoimmune or endocrine causes of diarrhoea, but a CT scan showed extensive walled-off necrosis (WON) due to the pancreatitis. Colonoscopy revealed two colonic fistulae, which were later confirmed by magnetic resonance cholangiopancreatography as pancreaticocolonic fistulae (PCF).The patient was treated with the placement of a lumen-apposing metal stent, multiple endoscopic necrosectomies and broad-spectrum antibiotics. The patient's diarrhoea resolved after the reduction in the size of the WON. She was discharged in good condition after a prolonged hospital course. This case highlights the importance of considering PCF in patients with WON and persistent diarrhoea, as a rare complication of necrotising pancreatitis.