## H. pylori and MALT Lymphoma **Key Point:** Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is strongly associated with *Helicobacter pylori* infection in 90% of cases. ### Pathogenic Mechanism 1. Chronic H. pylori infection triggers persistent antigen stimulation 2. Polyclonal B-cell proliferation in gastric MALT 3. Accumulation of genetic aberrations (e.g., t(11;18) translocation) 4. Evolution to monoclonal lymphoma **High-Yield:** H. pylori eradication therapy (triple or quadruple regimen) achieves lymphoma regression in 60–90% of early-stage gastric MALT lymphomas without translocation t(11;18). ### Clinical Features of Gastric MALT Lymphoma - **Presentation:** Often asymptomatic, discovered incidentally on endoscopy - **Endoscopic findings:** Nodular or ulcerated gastric mucosa - **Histology:** Small lymphocytes infiltrating mucosa, with lymphoepithelial lesions - **Prognosis:** Indolent course; excellent response to H. pylori eradication in early stages **Clinical Pearl:** MALT lymphomas can arise in other sites (salivary glands, thyroid, lung) but gastric MALT is the most common and best-characterized. Extragastric MALT lymphomas are not associated with H. pylori. ### Diagnostic Algorithm ```mermaid flowchart TD A[Gastric MALT Lymphoma]:::outcome --> B{H. pylori positive?}:::decision B -->|Yes, Stage I| C[H. pylori eradication]:::action B -->|No or Stage II+| D[Chemotherapy or observation]:::action C --> E{Regression?}:::decision E -->|Yes| F[Cure achieved]:::outcome E -->|No| G[Assess for t(11;18)]:::action G --> H{t(11;18) present?}:::decision H -->|Yes| I[Chemotherapy required]:::action H -->|No| J[Repeat H. pylori eradication]:::action ``` **Mnemonic:** **HP-MALT** — Helicobacter pylori, MALT lymphoma (gastric origin).
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