Reproducible Topographic Phenotypes and Three-Phase Anatomical Evolution of Gastric Intestinal Metaplasia

Although Endoscopic Grading of Gastric Intestinal Metaplasia (EGGIM) is used for risk stratification, it remains poorly defined whether gastric intestinal metaplasia (IM) follows reproducible anatomic patterns or has structured evolution. We hypothesized that IM progresses and regresses through ordered topographic states.

We retrospectively analyzed 3335 endoscopies with real-time EGGIM scoring (2022-2025). Topographic coherence was quantified by cosine similarity, while directional severity gradients by Spearman's correlation. Longitudinal trajectories were reconstructed in 486 patients with paired examinations (> 6 months). Score changes were classified as low score-, mid score-, or high score-phase for endoscopic progression or regression, grouping five gastric sites into antrum, transitional zone, and corpus regions. Directionality was tested using paired Wilcoxon signed-rank tests.

Cross-sectionally, EGGIM score strata displayed highly reproducible topographic patterns (cosine similarity: 0.87-0.99), with a consistent antrum-to-corpus severity gradient (Spearman's ρ: 0.73). These patterns defined three phenotypes: antral-dominant, transitional, and corpus-involving. Longitudinally, endoscopic progression and regression of IM followed a mirrored anatomical pathway across these phenotypes. Antral changes dominated low-score progression and regression (p < 0.001). Mid-score evolution involved parallel antral and transitional zone changes (p < 0.001). High-score regression manifested as corpus score reduction (p < 0.001). High-score progression was infrequent and showed a non-significant trend toward corpus score progression (p = 0.063).

Gastric IM exhibits reproducible topographic phenotypes, and both cross-sectional and longitudinal findings support a three-phase anatomical framework from the antrum through the transitional zone to the corpus.