| Summary: | Most of the MALT-lymphoma of the stomach is generated in the antrum and it is macroscopically characterized by unclear boundaries, mucosa thickening or its ulceration. The MALToma generation is a many-phase process and it is a consequence of the chronic infection Helicobacter pylori. At an early stadium, the tumor is limited to the stomach mucosa while its growth depends on the immunological stimulation through H. pylori while the regression starts after the eradication of this bacterium. However, the tumor can progress into an aggressive phase invading deeper layers of the gastric wall and, along with the dissemination into the local lymph nodes, into distant places as well. At an advanced stage, the stomach MALT lymphomas do not depend upon the H. pylori mediated stimulation; thus, they do not respond to the H. pylori eradication therapy. Finally, the boundary MALT lymphomas can be transformed into aggressive tumors of a high degree of malignity. Immunological and genetic factors intervene into the genesis of gastric MALT lymphomas, often synergetic in their effects. The immune response of the host to H. pylori induces the activity of the B-cell population.During this chronic inflammatory disease, the genome becomes unstable; thus, it is possible that the genetic abnormalities like trisomy should develop in the B cells. The changed B cell clone is subjected to clone expansion gradually forming the MALT lymphoma. Further genetic developments such as complete inactivation of the tumor suppressant genes (p53 and pl6) and possible activation of c-wyconcogene by trans location or other disturbances can lead to the transformation of the MALT lymphoma into the MALT lymphoma of a high malignity level.
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