What is Antral Gastritis?
Antral gastritis is chronic inflammation of the gastric antrum (the lower portion of the stomach near the pylorus) that is most commonly caused by Helicobacter pylori infection and represents the initial stage of what can progress to atrophic gastritis with intestinal metaplasia. 1
Pathophysiology and Anatomic Distribution
Antral gastritis typically begins as inflammation in the antrum and incisura (the transitional zone between antrum and corpus). 1 In H. pylori-associated antral gastritis (HpAG), the atrophic changes arise initially in the incisura and antrocorporal transitional mucosa as small foci with loss of glands and intestinal metaplasia. 1 Over time, these foci coalesce to form larger patches of atrophic/metaplastic mucosa along the lesser curvature and antrum, eventually spreading to the corpus/fundus. 1
This anatomic pattern distinguishes HpAG from autoimmune gastritis (AIG), which characteristically shows corpus-predominant atrophy with antral sparing. 1 However, if antral atrophy is seen in a patient with otherwise corpus-predominant disease, concomitant HpAG should be considered. 1
Histopathologic Features
The diagnosis of antral gastritis must be confirmed by histopathology. 1 The inflammatory process involves:
- Chronic inflammation with lymphocytic infiltration of the gastric mucosa 2, 3
- Progressive glandular loss (atrophy) that develops after years of mucosal inflammation 1
- Intestinal metaplasia (IM), which is the most frequently diagnosed histopathologic manifestation and almost invariably implies the diagnosis of atrophic gastritis 1
- Metaplastic replacement where gastric glands may be replaced with connective tissue (nonmetaplastic atrophy) or different epithelium (metaplastic atrophy) 1
Etiology and Associated Conditions
H. pylori Infection
H. pylori is detected in approximately 90% of patients with antral gastritis and duodenal ulcer disease. 2 The organism colonizes the antral mucosa affected by chronic gastritis, and its presence is significantly correlated with grades 2 and 3 gastritis (p < 0.001). 2 Active chronic gastritis (grade 3) is seen in 65% of those with C. pylori and is not found in patients without the bacterium. 2
Association with Peptic Ulcer Disease
Chronic antral gastritis is much more commonly associated with gastric or duodenal ulcer compared to chronic body gastritis. 3 Antral gastritis has been described in up to 100% of patients with duodenal ulcer disease. 2 The natural history of chronic antral gastritis appears the same in asymptomatic individuals and patients with peptic ulcer, suggesting these conditions are involved in a common mucosal inflammatory process. 3
NSAID-Induced Gastritis
Chemical gastritis from chronic NSAID use can affect the antrum, though it is present in only a limited number of patients (approximately 9% in chronic NSAID users versus 5% in controls). 4 The presence of chemical gastritis is not strongly correlated with NSAID-induced damage, and in many cases of peptic ulcer or upper gastrointestinal bleeding in NSAID users, chemical gastritis alone cannot account for the mucosal damage. 4
Clinical Significance and Cancer Risk
The severity and topographic distribution of atrophic lesions are well-established determinants of gastric cancer risk. 1 The risk of progression from atrophic gastritis to gastric adenocarcinoma ranges from 0.1% to 0.3% per year, but may be higher depending on severity, extent, and concomitant intestinal metaplasia. 1
Extensive atrophy and metaplasia in the antrum are associated with increased gastric cancer risk, and incomplete (colonic-type) intestinal metaplasia carries a 3-fold higher cancer risk than complete type. 5
Important Clinical Pitfalls
Antral healing can occur at long-term follow-up, particularly after H. pylori eradication, which may cause CAG with initially documented antral involvement to mimic autoimmune gastritis over time. 6 In one study, 25.6% of patients showed complete antral healing at follow-up (mean 40.6 months), and atrophic antral gastritis regressed in 22.8% of patients. 6
Separate specimen jars are essential: Biopsies from the corpus and antrum/incisura must be placed in separately labeled jars to accurately assess the anatomic distribution and distinguish between HpAG and AIG. 1, 5
Intestinal metaplasia presence: Providers should recognize that the presence of intestinal metaplasia on gastric histology almost invariably implies the diagnosis of atrophic gastritis, requiring coordinated effort between gastroenterologists and pathologists to document extent and severity. 1