Incomplete Intestinal Metaplasia is Rare in Autoimmune Gastritis.

BACKGROUND: Incomplete intestinal metaplasia (IM) is reportedly associated with higher gastric cancer (GC) risk than its complete variant. AGA Guidelines recommend including IM subtyping in routine pathology reports. This study assesses the prevalence of complete versus incomplete IM in gastric conditions with different GC risks.

METHODS: IM-subtyping (complete versus incomplete) and grading (IM extension: G1: ≤30%; G2: >30%) were assessed in 386 patients with IM+ve gastric biopsy sets that included both antral and oxyntic samples. Cases were categorized as: a) IM foci in otherwise normal mucosa (n = 59); b) H. pylori gastritis (n = 138); c) reactive gastropathy (141); d) Autoimmune atrophic gastritis ([AIG] n = 48). Odds ratios (OR) and their 95%CI were used in comparing the prevalence of incomplete-IM and the correlation between subtype and IM extension.

RESULTS: Incomplete-IM was presents in 37.7% of patients with H. pylori gastritis; 8.3% of those with AIG; 5.0% of those with reactive gastropathy, and none of those with otherwise normal mucosa. Incomplete-IM was strongly associated with more extensive (G2-IM) mucosal intestinalization (OR=6.69; CI95%: 2.77 - 9.40).

CONCLUSION: Incomplete-IM is significantly more prevalent in conditions (H. pylori gastritis) known to carry a higher risk of GC, and is strongly associated with its extension. The low prevalence of incomplete IM in AIG (8.3%), and reactive gastropathy (5.2%) is in keeping with the low GC risk associated with these conditions.