Mistaken identity: an unexpected case of spontaneous cholecystocutaneous fistula formation

We describe the case of a 78-year-old woman who presented to the emergency department with a 2-week history of a superficially developing mass in the lower right abdominal wall, fluctuant and non-tender with overlaying erythematous skin changes. Though resembling an abdominal wall abscess and initially listed for a simple incision and drainage, diagnostic uncertainty encouraged further investigation. CT and ultrasound confirmed the mass appeared to be in continuity with the gallbladder fossa, with the lumen also containing small bowel medially. While awaiting a multidisciplinary team discussion, the patient re-presented with concern over discharge appearing at the site of the mass. On inspection, we noted black flecks and small stones. This case describes the unusual and rare presentation of a cholecystocutaneous fistula. The patient was managed conservatively and remains clinically well.