A 52-year-old Indian woman presents with progressive fatigue, glossitis, and paresthesias in her feet. Endoscopy reveals chronic atrophic gastritis of the fundus and body. Histology shows the change marked **B** in the diagram — replacement of gastric glands with goblet cells and absorptive epithelium. Serological testing is positive for anti-intrinsic factor and anti-parietal cell antibodies. Which of the following best explains the pathophysiological significance of the structure marked **B** in the context of this patient's autoimmune gastritis?

Explanation

## Why intestinal metaplasia represents the Correa cascade and increases cancer risk is right The structure marked **B** — intestinal metaplasia (replacement of gastric epithelium with goblet cells and absorptive cells) — is a hallmark of chronic atrophic gastritis and forms a critical step in the Correa cascade: chronic gastritis → atrophy → intestinal metaplasia → dysplasia → intestinal-type gastric adenocarcinoma. In autoimmune metaplastic atrophic gastritis (AMAG), autoimmune destruction of gastric parietal cells leads to achlorhydria and loss of intrinsic factor, triggering mucosal atrophy and metaplasia. This metaplastic change is not merely adaptive but represents a precancerous lesion associated with significantly increased risk of both intestinal-type gastric adenocarcinoma and gastric carcinoid tumors. Surveillance with periodic endoscopy and biopsy mapping (Sydney protocol) is indicated for extensive intestinal metaplasia, particularly in high-risk populations including Indians and East Asians. (Robbins 10e Ch 17) ## Why each distractor is wrong - **Acute inflammatory infiltrate reversible with PPI**: Intestinal metaplasia is a chronic, largely irreversible change representing epithelial differentiation, not acute inflammation. While PPIs may reduce acid and slow progression, they do not reverse established metaplasia. The chronic lymphoplasmacytic infiltrate (marked **C**) represents the inflammatory component, not **B**. - **Protective adaptation reducing acid**: Although metaplasia does reduce acid secretion, it is not a protective adaptation but rather a pathological consequence of chronic parietal cell loss. It indicates mucosal damage and increased malignant potential, not protection. - **Pathognomonic for H. pylori**: Intestinal metaplasia occurs in both H. pylori-related and autoimmune gastritis. This patient's positive anti-parietal cell and anti-intrinsic factor antibodies, fundal/body involvement, and B12 deficiency are diagnostic of AMAG, not H. pylori gastritis. H. pylori predominantly affects the antrum initially. **High-Yield:** Intestinal metaplasia is a precancerous lesion in the Correa cascade; its presence mandates surveillance, especially in AMAG and in Indian/East Asian populations with high gastric cancer incidence. [cite: Robbins 10e Ch 17]