[MALT lymphoma of the rectum: a case report treated by radiotherapy].

The mucosa-associated lymphoid tissue (MALT) lymphoma is a distinct clinical pathologic entity that develops in diverse anatomic locations such as the stomach, salivary gland, thyroid, lung, skin and breast. However, colorectal involvement is extremely rare. To our knowledge, only ten cases of primary rectal MALT lymphoma have been reported in the literature. We report a 46-year-old woman with rectal MALT lymphoma, which regressed after radiotherapy. The patient had rectal bleeding. Colonoscopy showed a pseudonodular and ulcerated big fold in the rectum. Microscopic and immunohistologic studies of the biopsy specimen showed typical features of low grade MALT lymphoma. Upper endoscopy showed chronic gastritis with lymphoid follicles but without any infiltration of lymphoma cells. Helicobacter pylori infection was confirmed by histology. No extra-intestinal involvement was found on the staging evaluation, which included computed tomography (CT) of the abdomen, chest, pelvis and a bone marrow biopsy. We attempted to eradicate H. pylori with a 7-day course of omeprazole, amoxycillin, and metronidazole. Eradication was proved successful by endoscopy. Repeated colonoscopy 4 months after the end of treatment showed that the rectal tumor had not regressed. Biopsy specimens confirmed the persistent infiltration of lymphoma cells. The patient was considered to be a non-responder to eradication therapy and was indicated for radiotherapy. He underwent a total of 34 Gy. Complete regression was confirmed by colonoscopic and histologic examination at 2 months after the end of treatment. He was followed up closely with colonoscopy, but no relapse of these lesions was detected after 12 months.