A Case of Gastric Juvenile-Type Polyposis With SMAD4 Mutation.

Juvenile polyposis syndrome (JPS) is a rare autosomal-dominant disorder characterized by the presence of multiple hamartomatous polyps in the gastrointestinal tract. JPS has been established to be attributable to SMAD4 mutations, which are frequently associated with severe gastric phenotypes and hereditary hemorrhagic telangiectasia. We report the case of a 39-year-old woman with a history of immature teratoma, who presented with persistent anemia and upper gastrointestinal bleeding. Endoscopy revealed multiple gastric polyps, including a 5-cm polyp at the cardia. She underwent repeated endoscopic mucosal resections, with the initial histopathologic findings being consistent with hyperplastic polyps. Next-generation sequencing identified a pathogenic SMAD4 mutation, confirming the diagnosis of gastric juvenile-type polyposis. This case highlights the importance of considering hereditary polyposis syndromes in patients with multiple gastric polyps and anemia, even in the absence of a family history. Early genetic testing facilitates accurate diagnosis and enables appropriate endoscopic surveillance and management, as well as screening for extra-gastrointestinal manifestations.