Delayed Transmural Migration of a Fish Bone Mimicking a Gastric Submucosal Tumor and Resulting in Lesser Sac Abscess: A Case Report

Introduction: Foreign body ingestion is a common clinical condition, with fish bones being the leading cause of gastrointestinal perforation. However, gastric wall perforation leading to a lesser sac abscess is extremely rare. Case presentation: A 65-year-old woman with a history of gastric GIST resection presented with epigastric pain. Retrospective review of endoscopy and CT from 21 months prior revealed a 25-mm gastric antrum lesion mimicking a submucosal tumor and localized inflammatory changes with a hyperdense linear structure. Current CT demonstrated a 49 × 29 mm lesser sac abscess containing a 21-mm linear foreign body. Diagnostic laparoscopy revealed a localized abscess cavity and fully migrated 25-mm fish bone. The gastric perforation site had completely self-sealed via fibrosis, requiring no closure. The patient recovered uneventfully after abscess drainage and foreign body removal. Conclusion: Delayed transmural migration of a fish bone can mimic a gastric submucosal tumor before causing a lesser sac abscess. Laparoscopic surgery is a safe, effective, and minimally invasive therapeutic approach.