A low grade, indolent B-cell lymphoma, usually associated with Helicobacter pylori infection. Morphologically it is characterized by a dense mucosal atypical lymphocytic (centrocyte-like cell) infiltrate with often prominent lymphoepithelial lesions and plasmacytic differentiation. Approximately 40% of gastric MALT lymphomas carry the t(11;18)(q21;q21). Such cases are resistant to Helicobacter pylori therapy. The disease is gastric mucosa-associated lymphoid tissue lymphoma (MONDO_0006226, a Monarch Disease Ontology id). Also known as: MALT lymphoma of stomach, MALT lymphoma of the stomach, MALToma of stomach, MALToma of the stomach, gastric MALT lymphoma, gastric MALToma, primary MALT lymphoma of stomach, primary MALT lymphoma of the stomach.