A 58-year-old man with chronic NSAID use for osteoarthritis presents with epigastric pain worsened by food intake and weight loss over 6 weeks. Upper endoscopy reveals a gastric ulcer on the lesser curve with the feature marked **A** (smooth regular heaped-out margins). Multiple biopsies are obtained from the ulcer edge and base. Which of the following best explains why multiple biopsies are MANDATORY for this gastric ulcer, despite its benign endoscopic appearance?