[A case of MALT lymphoma of the colon, stomach, and small intestine].

An 85-year-old man was diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma of the colon in 20XX. Although Helicobacter pylori eradication was performed as part of the treatment, it was ineffective. He was followed-up by colonoscopy for 4 years without additional treatment and there was no interval change;however, he was lost to follow-up 6 years after the first visit. Nine years after the initial diagnosis, he presented with new MALT lymphoma lesions in the stomach and small intestine. Genetic analysis showed that a biopsy specimen was positive for API2/MALT1 fusion gene, and IgH rearrangement showed monoclonal banding between colon and stomach. This suggested disseminated monoclonal API2/MALT1-positive MALT lymphoma of the colon, stomach, and small intestine. Careful attention should be paid to the appearance of multiple lesions in MALT lymphoma.