S5196 Malignant Gallbladder Adenocarcinoma in a Patient With Prader-Willi Syndrome: A Complex Case of Obstructive Jaundice and Gastric Outlet Obstruction Requiring Palliative Gastrojejunostomy

Introduction: Gallbladder adenocarcinoma is an uncommon but highly aggressive malignancy, representing approximately 1.2% of all cancers globally. It is often diagnosed at an advanced stage due to vague, nonspecific symptoms. To date, gallbladder cancer has rarely been reported in patients with Prader-Willi syndrome. We present a unique case of advanced gallbladder adenocarcinoma in a middle-aged man with Prader-Willi syndrome, complicated by malignant biliary and gastric outlet obstruction requiring endoscopic palliation. Case Description: A 46-year-old man with Prader-Willi syndrome, diabetes, hypothyroidism, and seizure disorder presented with persistent vomiting and poor oral intake. Due to cognitive impairment, history was obtained from his parents. Imaging showed a gallbladder mass with porta hepatis involvement and extensive lymphadenopathy. Endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) confirmed a malignant-appearing 8.5 cm gallbladder mass with bulky para-aortic and gastrohepatic lymph nodes. Fine needle aspiration confirmed gallbladder adenocarcinoma. A 10 mm × 8 cm covered biliary metal stent was placed. Weeks later, he returned with worsening vomiting and jaundice. Labs revealed elevated bilirubin (25.2 mg/dL), alkaline phosphatase (2,067), and hyponatremia (Na 128). Imaging showed biliary stent occlusion, hepatic metastases, and gastric outlet obstruction from extrinsic lymphadenopathy. Repeat ERCP revealed complete biliary stent occlusion. A duodenal stent and EUS-guided gastrojejunostomy were placed, followed by deployment of a new 10 mm × 10 cm uncovered biliary stent through the existing one. Despite technical success, the patient's functional decline continued. Due to poor performance status and metastatic burden, chemotherapy was not pursued. He was transitioned to hospice after goals-of-care discussions. Discussion: This case underscores the diagnostic and therapeutic challenges of managing advanced gallbladder adenocarcinoma in a patient with Prader-Willi syndrome. The patient developed malignant biliary and gastric outlet obstruction, requiring dual endoscopic palliation, including EUS-guided gastrojejunostomy—a novel approach aimed at improving quality of life. Multidisciplinary collaboration was critical in balancing the procedural risks, disease progression, and overall goals of care. EUS-guided interventions may serve as valuable tools in managing complex gastrointestinal obstruction in select patients with limited options.