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Gastric lymphoma refers to primary or secondary malignant lymphoid proliferation involving the stomach. It is the most common site of extranodal non-Hodgkin’s lymphoma (NHL), accounting for 30–40% of all gastrointestinal lymphomas and about 3–5% of gastric malignancies.

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Etiopathogenesis

Histological subtypes:

• Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma): Indolent type, strongly associated with Helicobacter pylori infection.
• Diffuse large B-cell lymphoma (DLBCL): More aggressive, may arise de novo or via transformation from MALT.
• Rare subtypes: mantle cell, follicular, T-cell lymphoma.

Risk factors:

• H. pylori–induced chronic gastritis (major etiologic factor for MALT).
• Immunosuppression, HIV/AIDS, post-transplant states.
• Autoimmune disorders (e.g., Sjögren’s syndrome, Hashimoto thyroiditis).
• Chronic inflammation leading to lymphoid tissue acquisition in gastric mucosa.

Pathogenesis:

Chronic H. pylori infection → persistent antigenic stimulation → monoclonal B-cell proliferation → MALT lymphoma → possible transformation into DLBCL.

Clinical Features

• Dyspepsia, epigastric pain, anorexia, weight loss.
• Upper GI bleed, vomiting, early satiety.
• B-symptoms are uncommon in MALT, more frequent in DLBCL.
• Rarely, perforation or gastric outlet obstruction.