S2171 A Case of Colorectal MALToma

Abstract

Introduction: Non-Hodgkin lymphoma is classified as nodal and extranodal. Extranodal lymphoma frequently involves the stomach and is associated with H. Pylori infection. Colonic involvement, however, is rare. We present a case of MALT lymphoma that was found incidentally on colonoscopy. Case Description/Methods: A 73-year-old male with a history of diabetes presented for surveillance colonoscopy. Previous colonoscopy reports were unavailable, but the patient endorsed a history of benign polyps. Colonoscopy revealed a patchy area of inflammation and ulceration localized to the rectum and rectosigmoid colon. Biopsies demonstrated prominent lymphoid aggregates with inconclusive flow cytometry. He was referred to oncology who recommended further sampling. He underwent repeat colonoscopy 5 months later which demonstrated a 3 cm polyp in the cecum in addition to multiple segmental aphthae (uniform punctate lesions with surrounding erythema and central pallor) stretching from the distal sigmoid colon to the rectum. Pathology of the polyp demonstrated several lymphoid aggregates and rectosigmoid biopsies demonstrated prominent lymphoid aggregates that were positive for CD20, CD79a, BCL-2. Findings overall were consistent with extranodal marginal zone lymphoma. PET scan demonstrated diffuse lymphadenopathy, splenomegaly, and intense hypermetabolic activity throughout the colon. Stool studies were not obtained. The patient was recommended for chemotherapy with weekly rituximab which has been well tolerated to date. Discussion: Colorectal lymphoma is a rare occurrence, and represents less than 1% of all colorectal malignancies. Furthermore MALTomas present as primary colonic lymphomas in only 2.5% of cases. MALTomas predominate in men aged 50-70 years old and are associated with chronic immunosuppression and H. pylori infection when found in the stomach, although this does not necessarily hold true when found in the colon. Patients can present with symptoms of abdominal pain, obstruction, or GI bleeding. Endoscopic appearance of MALTomas is not well defined and can range from a single polypoid lesion to ulcerated mucosa or erosions. A combination of surgery, chemotherapy, and radiation is available for treatment of advanced disease.Primary colonic lymphoma is rare and there are only a few cases reported in the literature. Although rare, it is important to keep NHL in the differential when polypoid or ulcerated lesions are found on colonoscopy.