What happened, in summary

A 46-year-old man was referred for treatment of a small stomach lesion that had first been found during routine endoscopy 6 years earlier. The lesion had remained stable in size and appearance, and earlier biopsy had described an intestinal-type adenoma. Tests for Helicobacter pylori were negative, and the surrounding stomach lining showed no atrophy.

At the referral hospital, endoscopy showed a 10-mm reddish, flat elevated lesion with a central depression in the gastric antrum. Its appearance resembled verrucous gastritis rather than an obvious cancer. Magnified endoscopy showed subtle irregularities, and clinicians removed the lesion endoscopically because adenocarcinoma was suspected.

Pathology changed the diagnosis: the depressed portion contained well-differentiated tubular adenocarcinoma confined to the stomach lining. Additional staining supported a gastrointestinal-type tumor arising in H. pylori-uninfected mucosa. The key clinical feature was the unusually benign-looking lesion and its long period of observation before endoscopic removal established the diagnosis of early gastric adenocarcinoma.