Bouveret syndrome secondary to a cholecystoduodenal fistula in a patient with locally advanced cholangiocarcinoma

Bouveret syndrome is a rare form of gallstone ileus characterized by gastric outlet obstruction caused by the impaction of a large gallstone that migrates through a biliary-enteric fistula. Its occurrence in patients with active biliary malignancy is exceptionally uncommon and poses significant diagnostic and therapeutic challenges. We report the case of a 63-year-old woman with locally advanced, unresectable cholangiocarcinoma who presented with acute abdominal pain, hemodynamic instability, and severe metabolic derangement during first-line systemic therapy. Computed tomography revealed a contained gallbladder perforation with a cholecystoduodenal fistula and a large gallstone impacted in the duodenal bulb, causing secondary gastric dilatation consistent with Bouveret syndrome. Due to clinical deterioration and unfavorable local inflammatory conditions, surgical management was selected. Exploratory laparotomy was performed, and the stone was mobilized retrogradely into the stomach, followed by anterior gastrotomy and successful extraction. The management of Bouveret syndrome remains controversial, particularly in patients with advanced malignancy, as endoscopic treatment has limited success in cases involving large stones or severe inflammation. In this patient, stone size, local anatomy, and oncologic status justified a palliative surgical approach focused on symptom relief and damage control. Bouveret syndrome in the setting of advanced cholangiocarcinoma is rare and associated with poor prognosis; however, individualized, multidisciplinary decision-making is essential, and surgical intervention remains a valid option in unstable patients or when endoscopic management is not feasible.