Gastric mucosa-associated lymphoid tissue lymphoma.

The connection between Helicobacter pylori and gastric mucosa-associated lymphoid tissue (MALT) lymphoma is well established. H. pylori infection causes an immunological response, leading to chronic gastritis with formation of lymphoid follicles within the stomach. These lymphoid follicles resemble nodal tissues found throughout the body and are composed of reactive T cells and activated plasmal cells and B cells. The B cells are responsible for initiating a clonal expansion of centrocyte-like cells that form the basic histology of MALT lymphoma. Early diagnosis of MALT lymphoma is difficult but essential for adequate treatment. Clinical symptoms are vague and varied, with abdominal pain being a common presenting complaint. The endoscopic appearance of this tumor is varied and can be infiltrative, exophytic, or ulcerative. In addition, the tumor can have a multifocal distribution, and therefore aggressive tissue sampling is crucial for diagnosis. Endoscopic ultrasound is essential to document the extent of disease and is more accurate than CT scan in detection of spread to perigastric lymph nodes. Lesions that are confined to the mucosa or submucosa of the gastric wall are believed to be dependent on H. pylori stimulation and therefore can be successfully treated with H. pylori eradication. Those MALT lymphomas that present at more advanced stages require more aggressive management and can be treated with surgical resection, radiation, or chemotherapy. Follow-up is critical in all patients who have been treated with H. pylori eradication and consists of multiple endoscopic biopsies for histological and molecular studies as well as endoscopic ultrasound at 3, 6, and 12 months after treatment. The reappearance of MALT lymphomas has been seen years after treatment, and therefore follow-up of these patients should be indefinite.