Concurrent gastric and colonic low-grade mucosa-associated lymphoid tissue lymphomata in a patient without Helicobacter pylori infection

Mucosa-associated lymphoid tissue (MALT) lymphomata observed simultaneously in the stomach and colon are rare. We report concurrent gastric and colonic low-grade MALT lymphomata that originated from the same clone in a 58-year-old Japanese man without Helicobacter pylori infection. Endoscopy showed multiple erosive lesions in the gastric body and antrum, and a single flat elevation with an irregular margin in the sigmoid colon. Histopathological findings of both lesions suggested low-grade MALT lymphoma. Lymphoepithelial lesions were evident in the gastric lesions, but not in the colonic lesion. Southern blot analysis of lymphoma cells revealed the same immunoglobulin heavy-chain rearrangement pattern. The chromosomal translocation t(11;18)(q21;q21) was also observed. After six courses of cyclophosphamide, doxorubicin, vincristine and predonisolone, the gastric lesions disappeared endoscopically, while the colonic lesion persisted. A sigmoidectomy was consequently performed. The chromosomal translocation may be related to the pathogenesis of the present MALT lymphoma case without H. pylori infection. It is interesting that the gastric and colonic lesions differed in response to treatment and in their endoscopic and histologic features, despite having the same origin.