Autoimmune gastritis: novel clues to histological diagnosis

To compare the histological features of a consecutive biopsy series of autoimmune gastritis (AIG) with other forms of chronic gastritis to identify morphological clues to the diagnosis.

Morphological features in gastric biopsies were examined in 42 prospectively identified patients with AIG without concomitant neoplasia (n = 184 biopsies), 50 normal controls (NGB; n = 118 biopsies), 52 Helicobacter associated gastritis (HPG; n = 123 biopsies), 16 multifocal atrophic gastritis (MAG; n = 62 biopsies) and 50 chronic pangastritis without defined cause (CG; n = 117 biopsies).

In AIG, inflammation was characterised by lymphocyte infiltration into the epithelium (98%), basal lymphoid aggregates (82.7%), basal predominance (59.6%), eosinophil infiltration [mean 34.5/high power field (HPF), >30  eosinophils/HPF in 46.1%] and neutrophil infiltration (44.2%). Architectural abnormality was characterised by muscularis mucosae thickening (92.9%) and gland irregularity (86.5%). Pancreatic metaplasia was identified in 21.2% of cases. Compared to NGB, HPG, MAG and CG, AIG displayed more eosinophil infiltration (p < 0.001) and more frequent lymphocyte infiltration of the epithelium, basal predominant inflammation and pancreatic acinar metaplasia (all p > 0.05).

Basal predominance of inflammation, lymphocyte infiltration into gland epithelium, prominent eosinophils, architectural irregularity and muscularis mucosae thickening are common in AIG and are helpful when biopsy site and/or clinical history is uncertain.