MALT lymphoma
Encyclopedia
MALT lymphoma 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 cell
s in the marginal zone
of the MALT, and is also called extranodal marginal zone B cell lymphoma.
as a result of the presence of Helicobacter pylori
.
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
).
), then 70–80% of patients will have a complete regression on treatment with antibiotic
eradication of H. pylori.
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, is predictive of poor response to eradication therapy.
Two other genetic
alterations are known:
These seem to turn-on the same pathway as API2-MLT (i.e., that of NF-κB). They both act upon IGH
, which is at the locus 14q32.
, 8% of cases are MALT lymphomas.
Lymphoma
Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...
involving the mucosa-associated lymphoid tissue
Mucosa-associated lymphoid tissue
The mucosa-associated lymphoid tissue is the diffusion system of small concentrations of lymphoid tissue found in various sites of the body, such as the gastrointestinal tract, thyroid, breast, lung, salivary glands, eye, and skin.MALT is populated by lymphocytes such as T cells and B cells, as...
(MALT), frequently of the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
, but virtually any mucosal site can be afflicted. It is a cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
originating from B cell
B cell
B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...
s in the marginal zone
Marginal zone
The marginal zone is the region at the interface between the non-lymphoid red pulp and the lymphoid white-pulp of the spleen. A marginal zone also exists in lymph nodes.-Composition and markers:It is composed of cells derived...
of the MALT, and is also called extranodal marginal zone B cell lymphoma.
Associations
Gastric MALT lymphoma is frequently associated (72–98%) with chronic inflammationInflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
as a result of the presence of Helicobacter pylori
Helicobacter pylori
Helicobacter pylori , previously named Campylobacter pyloridis, is a Gram-negative, microaerophilic bacterium found in the stomach. It was identified in 1982 by Barry Marshall and Robin Warren, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions that were...
.
The initial diagnosis is made by biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
of suspicious lesions on esophagogastroduodenoscopy
Esophagogastroduodenoscopy
For other expansions of the initialism "OGD", see the disambiguation page.In medicine , esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract up to the duodenum...
(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
Sjögren's syndrome
Sjögren's syndrome , also known as "Mikulicz disease" and "Sicca syndrome", is a systemic autoimmune disease in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
and Hashimoto's thyroiditis
Hashimoto's thyroiditis
Hashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease in which the thyroid gland is gradually destroyed by a variety of cell- and antibody-mediated immune processes. It was the first disease to be recognized as an autoimmune disease...
, and MALT lymphoma of the salivary gland
Salivary gland
The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
and the thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
).
Treatment
If the disease is limited to the stomach (which is assessed with computed tomographyComputed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
), then 70–80% of patients will have a complete regression on treatment with antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
eradication of H. pylori.
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
Refractory
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above...
on antibiotics, chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
may need to be considered.
A t(11;18)(q21;q21) chromosomal translocation
Chromosomal translocation
In genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes, the occurrence of which is common in cancer. It is detected on...
, giving rise to a API2-MLT
MALT1
Mucosa-associated lymphoid tissue lymphoma translocation protein 1 is a protein that in humans is encoded by the MALT1 gene.-Further reading:...
fusion gene, is predictive of poor response to eradication therapy.
Two other genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
alterations are known:
- t(1;14)(p22;q32) which deregulates BCL10BCL10B-cell lymphoma/leukemia 10 is a protein that in humans is encoded by the BCL10 gene.-Interactions:BCL10 has been shown to interact with CARD10, CARD11, MALT1, TRAF2, IKBKG and CARD9.-Further reading:...
, at the locus 1p22. - t(14;18)(q32;q21), which deregulates MALT1MALT1Mucosa-associated lymphoid tissue lymphoma translocation protein 1 is a protein that in humans is encoded by the MALT1 gene.-Further reading:...
, 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
IGH@
Immunoglobulin heavy locus, also known as IGH@, is a region on human chromosome 14 that contains a gene for the heavy chains of human antibodies .-Further reading:...
, which is at the locus 14q32.
Epidemiology
Of all cancers involving the same class of blood cellLymphoproliferative disorders
Lymphoproliferative disorders refer to several conditions in which lymphocytes are produced in excessive quantities. They typically occur in patients who have compromised immune systems...
, 8% of cases are MALT lymphomas.