MALT lymphoma is a form of lymphoma involving the lymphoid tissue, frequently of the stomach. MALT lymphoma is a cancer of the B-cell lymphocytes. It usually affects older people who are in their 60s.

Zucca, E., et al. "The Gastric Marginal Zone Lymphoma of MALT Type." Blood 96 (July 2000): 410-19.

It is unusual for masses recognizable as tumors to be seen upon examination. Definitive diagnosis of MALT lymphoma requires a biopsy, in which a bit of tissue is removed from the stomach or other involved site.

It may be the case that in these patients, the MALT lymphoma may have already progressed to a point where high-grade lesions, not observed in the original biopsies, were resistant to the initial treatment.

This is a type of cancer that isn't produced in the nodes but through other organs. Most patients diagnosed with malt lymphoma find that this cancer is generally diagnosed before it spreads to a larger area of the body.