A 62-year-old woman presents with 3 months of epigastric pain and dyspepsia. Upper endoscopy reveals erythematous nodular mucosa in the antrum (marked **A** in the diagram) with loss of normal vascular pattern. Multiple biopsies show small centrocyte-like lymphocytes with lymphoepithelial lesions; immunohistochemistry is CD20+, CD5−, CD10−, CD23−. H. pylori is detected on urease testing. The patient is staged as Lugano stage I. Which of the following is the most appropriate first-line management for this gastric MALT lymphoma?

Question

Accepted Answer

C. H. pylori eradication therapy (PPI + clarithromycin + amoxicillin for 14 days). ## Why H. pylori eradication therapy is right

Gastric MALT lymphoma (mucosa-associated lymphoid tissue lymphoma) is the most common extranodal lymphoma, accounting for ~40% of gastric lymphomas. The pathogenesis is driven by chronic antigenic stimulation by *Helicobacter pylori* (present in >90% of cases), which recruits reactive lymphoid tissue to the normally MALT-free gastric mucosa. The characteristic endoscopic appearance shown at **A** — erythematous nodular antral mucosa with loss of vascular pattern — is typical. For stage I disease (confined to mucosa/submucosa), H. pylori eradication with standard triple therapy (PPI + clarithromycin + amoxicillin) for 14 days is the established first-line treatment. Complete regression occurs in 60–80% of cases within 12–18 months following successful eradication. Endoscopic surveillance every 3 months for 1 year, then 6-monthly, is required to monitor response. This patient has no adverse prognostic features (no mention of t(11;18) translocation or deep submucosal invasion) and is therefore an ideal candidate for eradication therapy.

## Why each distractor is wrong

- **Rituximab monotherapy followed by endoscopic surveillance**: Rituximab is reserved for advanced disease or cases with adverse molecular features (e.g., t(11;18)-positive) that are resistant to H. pylori eradication. It is not first-line for stage I disease in an H. pylori-positive patient.
- **Low-dose involved-field radiotherapy (24–30 Gy)**: Radiotherapy is highly effective (>90% complete response) but is reserved for t(11;18)-positive cases, those with deep submucosal invasion, or stage IIE+ disease that fails eradication therapy. It is not first-line for stage I, H. pylori-positive MALT lymphoma.
- **Chemotherapy with bendamustine and rituximab**: This immunochemotherapy combination is used for advanced or refractory disease, not for early-stage, H. pylori-positive MALT lymphoma amenable to eradication.

**High-Yield:** Gastric MALT lymphoma is H. pylori-driven in >90% of cases; eradication therapy achieves complete remission in 60–80% of stage I–II patients within 12–18 months.

[cite: Harrison's 21e Ch 109; Lugano staging; Wotherspoon Lancet 1991]

Answer

A. Rituximab monotherapy followed by endoscopic surveillance

Answer

B. Chemotherapy with bendamustine and rituximab

Answer

D. Low-dose involved-field radiotherapy (24–30 Gy) to the stomach

Explanation

Why H. pylori eradication therapy is right

Why each distractor is wrong

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