We report a case of a male patient in his 70s with Borrmann type 4 gastric cancer, accompanied by obstructive jaundice and duodenal invasion. He was referred to our institution due to unexplained liver dysfunction and dilation of the common bile duct. Upon undergoing upper gastrointestinal endoscopy, duodenal stenosis was identified. A biopsy from a lesion located in the greater curvature of the gastric vestibule revealed poorly differentiated adenocarcinoma, specifically signet-ring cell carcinoma (Group 5). Due to suspected peritoneal dissemination from advanced gastric cancer, which led to bile duct stricture, ureteral invasion, and bladder involvement, percutaneous transhepatic biliary drainage and chemotherapy were initiated to alleviate the obstructive jaundice. Four months post-treatment initiation, the duodenal stenosis showed improvement, resulting in internal drainage. However, liver dysfunction attributed to immune-related adverse events (irAE) necessitated the discontinuation of chemotherapy 9 months after treatment. Ultimately, disease progression led to patient demise.
