MALT lymphoma

MALT lymphoma is a form of non-Hodgkin lymphoma (NHL) involving the mucosa-associated lymphoid tissue (MALT), frequently of the stomach, but virtually any mucosal site can be afflicted. It is a cancer originating from B cells in the marginal zone of the MALT.

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Associations

Gastric MALT lymphoma is frequently associated (72-98%) with chronic inflammation as a result of the presence of Helicobacter pylori. ^[1]

The initial diagnosis is made by biopsy of suspicious lesions on esophagogastroduodenoscopy (EGD, upper endoscopy). Simultaeneously tests for H pylori are also done to detect the presence of this microbe.

In other sites, chronic immune stimulation is also suspected in the pathogenesis (e.g. association between chronic autoimmune diseases such as Sjögren's syndrome and Hashimoto's thyroiditis, and MALT lymphoma of the salivary gland and the thyroid).

Treatment

If the disease is limited to the stomach (which is assessed with computed tomography), then 70-80% of patients will have a complete regression on treatment with antibiotic eradication of H. pylori. ^[2]

Others may be effectively controlled with the use of radiotherapy, or surgery. Both modalities may be curative in localized disease.

In contrast, if the disease has spread or has been refractory on antibiotics, chemotherapy may need to be considered.

A t(11;18)(q21;q21) chromosomal translocation, giving rise to a AP12-MLT fusion gene, is predictive of poor response to eradication therapy. ^[3]

Two other genetic alterations, t(1;14)(p22;q32) and t(14;18)(q32;q21), which deregulate BCL10 and MALT1-genes respectively, and seem to turn-on the same pathway as API2-MLT (i.e., that of NF-kB).

References

1. ^ Parsonnet J, Hansen S, Rodriguez L, Gelb A, Warnke R, Jellum E, Orentreich N, Vogelman J, Friedman G (1994). "Helicobacter pylori infection and gastric lymphoma.". N Engl J Med 330 (18): 1267-71. PMID 8145781.
2. ^ Bayerdörffer E, Neubauer A, Rudolph B, Thiede C, Lehn N, Eidt S, Stolte M (1995). "Regression of primary gastric lymphoma of mucosa-associated lymphoid tissue type after cure of Helicobacter pylori infection. MALT Lymphoma Study Group.". Lancet 345 (8965): 1591-4. PMID 7783535.
3. ^ Liu H, Ruskon-Fourmestraux A, Lavergne-Slove A, Ye H, Molina T, Bouhnik Y, Hamoudi R, Diss T, Dogan A, Megraud F, Rambaud J, Du M, Isaacson P (2001). "Resistance of t(11;18) positive gastric mucosa-associated lymphoid tissue lymphoma to Helicobacter pylori eradication therapy.". Lancet 357 (9249): 39-40. PMID 11197361.