Gastritis Histology and Updated Staging
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Direct answer
Five biopsies, mapped to five mucosal stations, turn gastritis from an adjective into a stage. The Sydney protocol samples antrum (lesser and greater curve) twice, incisura once and corpus twice, so that Helicobacter-associated, antrum-predominant gastritis can be separated from corpus-restricted autoimmune gastritis and from atrophy that carries cancer risk. Activity means neutrophils; chronicity means mononuclear cells; atrophy and intestinal metaplasia are scored per site and aggregated into OLGA (histologic atrophy) or OLGIM (metaplasia) stages 0 to IV, with stage III-IV disease — severe atrophic metaplastic gastritis — the group in whom endoscopic surveillance is considered.
What you must remember
- Sydney mapping: two antral biopsies about 2-3 cm from the pylorus, one at the incisura, two from the corpus (greater and lesser curve); the report states topography, morphology and aetiology.
- H. pylori: curved bacilli in the surface mucus; Giemsa is the classic stain, immunohistochemistry the most sensitive — particularly after eradication attempts or with low bacterial loads; lymphoid follicles with germinal centres are the host signature.
- Activity versus chronicity: neutrophils in the epithelium define active gastritis (an eradication indicator); plasma cells and lymphocytes define chronic inflammation.
- OLGA/OLGIM staging: atrophy (or intestinal metaplasia for OLGIM) scored 0-3+ across the five Sydney sites yields stages 0-IV; stage III-IV carries materially increased gastric cancer risk and is the surveillance group.
- Autoimmune gastritis: corpus-restricted atrophy with antral sparing, loss of parietal cells, pseudopyloric (SPEM) and intestinal metaplasia, ECL hyperplasia on chromogranin/synaptophysin (linear and micronodular), antiparietal-cell and anti-intrinsic-factor antibodies, hypergastrinaemia, and type 1 gastric neuroendocrine tumour risk.
- Reactive gastropathy: foveolar hyperplasia with corkscrew glands, smooth muscle fibres in the lamina propria, oedema and vascular congestion with minimal inflammation — NSAIDs and bile, not infection.
- Other flags: Helicobacter heilmannii (longer, tighter spirals, rare), MALT lymphoma surveillance in H. pylori-positive gastritis, and eradication-induced changes that make organisms scarce.
Why the incisura earns its own biopsy
Two patients, two biopsies, one lesson. The first report reads "chronic active gastritis, H. pylori positive" from a single antral biopsy — adequate for eradication, silent about the corpus. The second patient had the full Sydney set: antrum shows complete atrophy with metaplasia, corpus is normal — an antral-predominant pattern. Had the atrophy sat in the corpus instead, with antro-corporal dissociation, autoimmune gastritis would be the working diagnosis and parietal-cell antibodies would follow. The incisura matters because intestinal metaplasia concentrates there first; missing it understages the patient from OLGA II to OLGA 0, and with it the surveillance conversation disappears. OLGIM was proposed because pathologists vary more in grading plain atrophy than metaplasia; using metaplasia as the surrogate trades some sensitivity for interobserver reliability — a trade-off worth stating in an exam answer.
Where students slip
Activity is the classic confusion: neutrophils mean activity and eradication-worthy infection, while lymphocytes alone mean chronic gastritis — a report that says "chronic active" for a purely mononuclear infiltrate has mislabelled both. Students also diagnose autoimmune gastritis from corpus atrophy without checking the antrum; antro-corporal dissociation is the diagnostic architecture, and absent antibodies do not exclude it. Third, Helicobacter density falls after any antibiotic exposure, so a negative Giemsa with follicular gastritis deserves immunohistochemistry before the organism is declared absent. In vivas, the MALT connection is the favourite closer — H. pylori-associated lymphoid tissue is the soil for marginal zone lymphoma, and eradication is first-line therapy for stage I disease.
Frequently asked questions
Which five sites does the Sydney protocol biopsy?
Antrum on lesser and greater curve, incisura, and corpus on greater and lesser curve — enabling topographic classification of gastritis.
What does OLGA staging measure?
Histologic atrophy scored across the five Sydney sites and aggregated into stages 0-IV; stage III-IV identifies the highest gastric cancer risk group.
How does OLGIM differ from OLGA?
OLGIM substitutes intestinal metaplasia for atrophy as the scored lesion, trading some sensitivity for better interobserver agreement.
What histology suggests autoimmune gastritis?
Corpus-restricted atrophy with parietal cell loss, pseudopyloric and intestinal metaplasia, ECL hyperplasia, and a spared antrum.
Why stain for H. pylori with immunohistochemistry?
It is more sensitive than Giemsa when organisms are scarce — after eradication therapy, with intestinal metaplasia, or in H. heilmannii infection.