What is atrophic gastritis?

What is Atrophic Gastritis?

Atrophic gastritis is a chronic inflammatory condition characterized by the loss of gastric glandular structures (parietal and chief cells) with or without replacement by metaplastic tissue, resulting in impaired gastric acid and pepsin secretion, and representing a precancerous condition with significant risk for gastric adenocarcinoma and neuroendocrine tumors. 1

Histopathologic Definition

The defining feature is glandular loss in the gastric mucosa, which can occur through two mechanisms 2:

• Non-metaplastic atrophy: Gastric glands are replaced by connective tissue (fibrous tissue) 2
• Metaplastic atrophy: Gastric glands are replaced by inappropriate glandular structures, including:
  • Pseudopyloric metaplasia (replacement by pyloric-type glands) 1, 3
  • Intestinal metaplasia (replacement by intestinal-type epithelium) 1, 3

The presence of intestinal metaplasia on gastric histology almost invariably implies the diagnosis of atrophic gastritis 4

Two Distinct Etiologic Types

H. pylori-Associated Atrophic Gastritis (Multifocal Pattern)

• Most common form with a rate ratio of 5.0 versus uninfected individuals 4
• Begins in the antrum and progresses to involve the corpus over time 5, 6
• Shows chronic inflammation with moderate to complete loss of oxyntic glands, pseudopyloric metaplasia, and intestinal metaplasia 1
• In marked atrophy, there may be complete absence of parietal and chief cells 1

Autoimmune Gastritis (Corpus-Restricted Pattern)

• Less common (0.5-2% prevalence), more likely in women 4
• Restricted to the corpus and fundus, sparing the antrum 6, 2
• Results from antibody-mediated destruction of parietal cells causing achlorhydria 6
• Shows complete absence of parietal and chief cells replaced by pseudopyloric and intestinal metaplasia 1
• Associated with ECL cell hyperplasia (linear and micronodular patterns) 1

Clinical Manifestations

Gastric Manifestations

• Often asymptomatic in early stages 6
• Dyspeptic symptoms when present 2
• Impaired secretion of gastric acid, pepsin, and intrinsic factor 7, 3

Extra-Gastric Manifestations

• Iron deficiency anemia (occurs in up to 50% of patients with corpus-predominant atrophy, often presenting before B12 deficiency) 4
• Vitamin B12 deficiency leading to pernicious anemia (in autoimmune type due to loss of intrinsic factor) 1, 6
• Hematologic, neurologic manifestations from micronutrient deficiencies 7

Endoscopic Appearance

Characteristic features include 1:

• Pale appearance of gastric mucosa
• Loss of gastric rugal folds
• Prominence of submucosal blood vessels due to thinning of atrophied epithelium
• Mildly nodular appearance in areas with intestinal metaplasia 1

Neoplastic Risk and Clinical Significance

This is NOT a benign condition 4:

• Gastric adenocarcinoma risk: 0.1-0.3% per year progression rate (similar to Barrett's esophagus) 4
• Type 1 gastric neuroendocrine tumor (NET) risk: 0.4-0.7% per year, particularly with autoimmune gastritis 4
• Type 1 gastric NETs represent 80-90% of all gastric NETs and are gastrin-dependent tumors 4
• The multistep progression follows: chronic inflammation → atrophic gastritis → intestinal metaplasia → dysplasia → gastric cancer 8

Associated Conditions

Patients with autoimmune gastritis should be screened for 1, 2:

• Autoimmune thyroid disease (most common association)
• Type 1 diabetes mellitus 2
• Other autoimmune disorders based on clinical presentation 1

Diagnostic Approach

Diagnosis requires histopathologic confirmation with topographical biopsies 1, 4:

• Two biopsies from corpus (greater and lesser curvature)
• Two biopsies from antrum (greater and lesser curvature)
• One biopsy from incisura 4

This allows determination of anatomic extent and histologic severity for proper risk stratification using OLGA or OLGIM staging systems 2

Management Implications

Patients with severe atrophic gastritis require 1:

• Endoscopic surveillance every 3 years for early gastric cancer detection 4, 2
• Evaluation and treatment of micronutrient deficiencies (iron and vitamin B-12) 1, 4
• H. pylori testing and eradication if positive 1, 4
• In autoimmune gastritis: screening for autoimmune thyroid disease and checking parietal cell antibodies (PCA) and intrinsic factor antibodies (IFA) 1, 4