MALT lymphoma is a form of
lymphomaLymphoma is a cancer that begins in the lymphocytes of the immune system and presents as a solid tumor of lymphoid cells. They often originate like balls in lymph nodes, presenting as an enlargement of the node...
involving the
mucosa-associated lymphoid tissueThe mucosa-associated lymphoid tissue is the diffuse 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 & B cells, as well...
(MALT), frequently of the
stomachIn most mammals, the stomach is a hollow, muscular organ of the gastrointestinal tract , between the esophagus and the small intestine. It is involved in the second phase of digestion, following mastication . The word stomach is derived from the Latin stomachus, which derives from the Greek word...
, but virtually any mucosal site can be afflicted. It is a
cancerCancer is a class of diseases in which a group of cells display uncontrolled growth , invasion , and sometimes metastasis...
originating from
B cellB 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 zoneThe 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.
Gastric MALT lymphoma is frequently associated (72-98%) with chronic
inflammationInflammation is 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 as well as initiate the healing process for the tissue. Inflammation is not a...
as a result of the presence of
Helicobacter pyloriHelicobacter pylori is a Gram-negative, microaerophilic bacterium that can inhabit various areas of the stomach and duodenum. It causes a chronic low-level inflammation of the stomach lining and is strongly linked to the development of duodenal and gastric ulcers and stomach cancer...
.
The initial diagnosis is made by
biopsyA biopsy is a medical test involving the removal of cells or tissues for examination. It is the 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
esophagogastroduodenoscopyIn medicine , esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract up to the duodenum...
(EGD, upper endoscopy).
MALT lymphoma is a form of
lymphomaLymphoma is a cancer that begins in the lymphocytes of the immune system and presents as a solid tumor of lymphoid cells. They often originate like balls in lymph nodes, presenting as an enlargement of the node...
involving the
mucosa-associated lymphoid tissueThe mucosa-associated lymphoid tissue is the diffuse 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 & B cells, as well...
(MALT), frequently of the
stomachIn most mammals, the stomach is a hollow, muscular organ of the gastrointestinal tract , between the esophagus and the small intestine. It is involved in the second phase of digestion, following mastication . The word stomach is derived from the Latin stomachus, which derives from the Greek word...
, but virtually any mucosal site can be afflicted. It is a
cancerCancer is a class of diseases in which a group of cells display uncontrolled growth , invasion , and sometimes metastasis...
originating from
B cellB 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 zoneThe 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.
Associations
Gastric MALT lymphoma is frequently associated (72-98%) with chronic
inflammationInflammation is 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 as well as initiate the healing process for the tissue. Inflammation is not a...
as a result of the presence of
Helicobacter pyloriHelicobacter pylori is a Gram-negative, microaerophilic bacterium that can inhabit various areas of the stomach and duodenum. It causes a chronic low-level inflammation of the stomach lining and is strongly linked to the development of duodenal and gastric ulcers and stomach cancer...
.
The initial diagnosis is made by
biopsyA biopsy is a medical test involving the removal of cells or tissues for examination. It is the 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
esophagogastroduodenoscopyIn 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 syndromeSjögren's syndrome is an autoimmune disorder in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
and
Hashimoto's thyroiditisHashimoto's thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease where the body's own T-cells attack the cells of the thyroid. It was the first disease to be recognised as an autoimmune disease....
, and MALT lymphoma of the
salivary glandThe salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into glucose...
and the
thyroidThe thyroid is one of the largest endocrine glands in the body. This gland is found in the neck inferior to the thyroid cartilage and at approximately the same level as the cricoid cartilage...
).
Treatment
If the disease is limited to the stomach (which is assessed with
computed tomographyComputed tomography is a medical imaging method employing tomography created by computer processing. Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation.CT...
), then 70-80% of patients will have a complete regression on treatment with
antibioticIn common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
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
refractoryA 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 made them applicable for structures, or as components of systems, that are exposed to environments above...
on antibiotics,
chemotherapyChemotherapy, in its most general sense, is the treatment of disease by chemicals especially by killing micro-organisms or cancerous cells. In popular usage, it refers to antineoplastic drugs used to treat cancer or the combination of these drugs into a cytotoxic standardized treatment regimen...
may need to be considered.
A t(11;18)(q21;q21)
chromosomal translocationIn genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes. A fusion gene may be created when the translocation joins two otherwise separated genes, an event which is common in cancer. It is detected on cytogenetics or a...
, giving rise to a
API2-MLTMucosa-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
geneticGenetics, , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding...
alterations are known:
- t(1;14)(p22;q32) which deregulates BCL10
B-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 MALT1
Mucosa-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-kBNF-κB is a protein complex that controls the transcription of DNA. NF-κB is found in almost all animal cell types and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, ultraviolet irradiation, oxidized LDL, and bacterial or viral antigens...
). They both act upon IGH, which is at the locus 14q32.
Epidemiology
Of all
cancers involving the same class of blood cellLymphoproliferative 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.