What happened, in summary

A 70-year-old woman was evaluated for upper-abdominal pain and severe anemia. Endoscopy showed numerous reddish polyps throughout the stomach and a large elevated lesion in the middle stomach. Initial biopsies of the polyps did not show cancer, but magnified endoscopy identified a suspicious area within the large lesion, and a targeted biopsy confirmed adenocarcinoma.

Endoscopic submucosal dissection removed the lesion and showed intramucosal well- to moderately differentiated adenocarcinoma arising in a background of gastric juvenile polyposis. Because she had persistent anemia and low protein levels, as well as concern for additional gastric cancers, she underwent laparoscopic total gastrectomy with lymph-node dissection. The removed stomach contained more than 200 polyps, another 25-mm intramucosal adenocarcinoma, and 4 small areas of dysplasia. No metastasis was found. Her anemia and low protein levels improved after surgery, and no recurrence or metastasis had been reported.

Genetic testing identified a pathogenic germline SMAD4 splice-site variant, supporting juvenile polyposis syndrome. Testing of relatives found the same variant in her daughter, who also had gastric polyposis. The case linked her extensive gastric polyposis and cancer to a hereditary syndrome requiring family-level genetic awareness.