MALT lymphoma

MALT lymphoma
Classification and external resources
Endoscopic image of gastric MALT lymphoma taken in body of stomach in patient who presented with upper GI hemorrhage. Appearance is similar to gastric ulcer with adherent clot.
ICD-9	200.3
ICD-O:	M9699/3
OMIM	604860
DiseasesDB	31339
MeSH	D018442

MALT lymphoma (MALToma) is a form of lymphoma 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, and is also called extranodal marginal zone B cell lymphoma.

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). Simultaneous 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 API2-MLT fusion gene,^[3] is predictive of poor response to eradication therapy.^[4]

Two other genetic alterations are known:

• t(1;14)(p22;q32) which deregulates BCL10, at the locus 1p22.
• t(14;18)(q32;q21), which deregulates MALT1, at the locus 18q21.

These seem to turn-on the same pathway as API2-MLT (i.e., that of NF-κB). They both act upon IGH,^[5] which is at the locus 14q32.

Epidemiology

Of all cancers involving the same class of blood cell, 8% of cases are MALT lymphomas.^[6]

See also

• Primary cutaneous marginal zone lymphoma

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. doi:10.1056/NEJM199405053301803. 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. doi:10.1016/S0140-6736(95)90113-2. PMID 7783535. 
3. ^ Noels H, van Loo G, Hagens S, et al. (April 2007). "A Novel TRAF6 binding site in MALT1 defines distinct mechanisms of NF-kappaB activation by API2middle dotMALT1 fusions". J. Biol. Chem. 282 (14): 10180–9. doi:10.1074/jbc.M611038200. PMID 17287209. http://www.jbc.org/cgi/pmidlookup?view=long&pmid=17287209. 
4. ^ 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. doi:10.1016/S0140-6736(00)03571-6. PMID 11197361. 
5. ^ Ye H, Gong L, Liu H, et al. (February 2005). "MALT lymphoma with t(14;18)(q32;q21)/IGH-MALT1 is characterized by strong cytoplasmic MALT1 and BCL10 expression". J. Pathol. 205 (3): 293–301. doi:10.1002/path.1715. PMID 15682443. 
6. ^ Turgeon, Mary Louise (2005). Clinical hematology: theory and procedures. Hagerstown, MD: Lippincott Williams & Wilkins. p. 283. ISBN 0-7817-5007-5. "Frequency of lymphoid neoplasms. (Source: Modified from WHO Blue Book on Tumour of Hematopoietic and Lymphoid Tissues. 2001, p. 2001.)"