Transformed gastric mucosa-associated lymphoid tissue lymphoma originating in the colon and developing metachronously after Helicobacter pylori eradication: A case report

( ) eradication treatment for primary gastric mucosa-associated lymphoid tissue (MALT) lymphoma has already been established. However, t (11;18) (q21;q21)/ translocation-positive lesions are a type of primary gastric MALT lymphoma in which a response to eradication treatment is difficult to achieve. In addition, trisomy 18 may be associated with diffuse large B-cell lymphoma (DLBCL) transformation of gastric MALT lymphoma. A 66-year-old man was diagnosed with MALT lymphoma in the ascending colon by colonoscopy and biopsy. Two years later, esophagogastroduodenoscopy revealed chronic atrophic gastritis that was positive for , and eradication treatment was administered. Two years and nine months later (at the age of 70), a new ulcerative lesion suggestive of MALT lymphoma appeared in the gastric body, and six months later, a similar lesion was also found in the fundus. One year later (4 years and 3 months after eradication), at the age of 72, the lesion in the gastric body had become deeper and had propagated. A biopsy revealed a pathological diagnosis of DLBCL. Both MALT lymphoma lesions in the ascending colon and DLBCL lesions in the stomach were positive for the t (11;18) (q21;q21)/ translocation, and trisomy 18q21 was also detected. After 6 courses of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) chemotherapy, all of the above lesions disappeared [complete remission (CR)], and CR has been maintained for more than 3 years. In addition, both the colonic and gastric lesions were proven to have the same clonality. Because the patient had a translocation with trisomy 18q21, it was thought that this gastric MALT lymphoma developed independently of infection and progressed.