Multifocal Colonic Ulcerations: An Unusual Presentation of Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma.

Introduction: Mucosa-associated lymphoid tissue (MALT) lymphoma is relatively uncommon and accounts for only 5% of all non-Hodgkin lymphomas. The most common site of extranodal involvement is the gastrointestinal (GI) tract, with most cases affecting the stomach (up to 75% of all GI MALT lymphomas). Colonic disease occurs in only 2.5% of cases, most commonly manifesting as a single polypoid lesion on endoscopic evaluation. Case Presentation: We present the case of a 61-year-old woman whose colonoscopy (after a positive fecal occult blood test as part of colorectal cancer screening) revealed superficially ulcerated pseudo-polypoid lesions in the ascending proximal colon and hepatic flexure; microscopical and immunohistochemical analysis of the tissue sample was compatible with MALT lymphoma. Staging computed tomography showed concomitant nodular pulmonary lesions, the largest being located in the superior left lobe and 34 mm in size. Due to the disseminated state of the disease, systemic treatment with bendamustine and rituximab was initiated. Up to the time of submitting this paper, the patient was still asymptomatic and under chemotherapy treatment. Conclusion: With this case report, we aim to demonstrate the diversity of presentation of MALT lymphoma as well as its less typical locations; gastroenterologists should have an awareness of these and a low suspicion threshold.