Mucosa-associated lymphoid tissue lymphoma

From IKE

mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) is the most common type of primary gastrointestinal neoplasm lymphoma in Canada. It arises from mucosa-associated lymphoid tissue which in turn arises as a consequence of Helicobacter pylori infection. The normal gastric mucosa is devoid of lymphoid tissue and other inflammatory cells, but under the stimulus of H. pylori infection, the mucosa becomes inflamed with the presence of lymphocytes and plasma cells.

T cells within the mucosa are stimulated by H. pylori to liberate cytokines, which in turn stimulate B cell proliferation.

MALT lymphomas present in middle-aged or elderly patients with non-specific dyspeptic symptoms or with evidence of bleeding or weight loss. Grossly, early tumors are typically non-descript and may present merely as thickened folds. Tumors may also present as more defined mass lesions – either large and polypoid or small and ulcerating.

MALT lymphomas are classified as either low or high grade based on their histological features. Typical low-grade tumors are characterized by a polymorphic infiltrate with atypical small lymphocytes, invasion of these lymphocytes into epithelial structures (to form lymphoepithelial lesions) and by the presence of reactive lymphoid follicles. The lymphoma ultimately spreads to involve regional lymph nodes. Low-grade MALT lymphomas are typically indolent and remain localized for a long time before systemic dissemination. Failure to respond to H. pylori eradication usually leads to treatment with chemotherapy, with or without surgery.