S3704 Explosive Diarrhea Found to Be Recurrent B-Cell Lymphoma

Introduction: Non-Hodgkin lymphoma (NHL) in the colon is a rare malignancy, accounting for 0.2-1.2% of all primary colon cancers and a minority of gastrointestinal lymphomas. The most common subtype is diffuse large B-cell lymphoma, but other subtypes such as marginal zone lymphoma of mucosa-associated lymphoid tissue, follicular lymphoma, and mantle cell lymphoma can also occur. Here we present a rare case of colon mass found to be recurrent B-cell non-Hodgkin’s lymphoma suggestive of extranodal marginal zone lymphoma. Case Description/Methods: A 74-year-old man with hypertension and NHL in the colon 10 years ago post resection presented to clinic with diarrhea. For 4 months, he had explosive diarrhea that persisted for 1 month and gradually improved. He has 3 bowel movements every morning with smaller ones throughout the day which are watery, small volume, associated with urgency, exacerbated by food and improved with kaopectate. Denied cramps, oily or greasy stools, mucousy stool, vomiting, fevers, abdominal pain, heartburn, melena, hematochezia, ill contacts, new medications or recent antibiotic use. Stool pathogen PCR was negative for all organisms tested. Fecal calprotectin was 1,500. Computed tomography (CT) abdomen/pelvis showed 15 × 10 × 9 cm mass in the left lower abdomen with evidence of previous bowel surgery and extensive mesenteric and retroperitoneal lymphadenopathy suggesting recurrent lymphoma. Colonoscopy showed patchy erythematous mucosa and 4 cm mass in ascending colon. Biopsy showed exuberant focally monotonous small lymphocytic nodular proliferation immunoreactive for CD-20 and BCL-2, highly suspicious for low grade extranodal marginal zone B-cell lymphoma, most compatible with extranodal marginal zone lymphoma. Discussion: NHL of the colon may cause diarrhea due to direct infiltration and disruption of the colonic mucosa by malignant lymphoid cells which can lead to mucosal ulceration, impaired absorption, and local inflammation. Additionally, the lymphoma may mimic inflammatory bowel disease by presenting with diarrhea, abdominal pain, and weight loss. Fecal calprotectin may be elevated due to mucosal inflammation leading to activation of neutrophils and migration into intestinal lumen. First-line treatment is systemic chemotherapy. Prognosis varies by histology and stage, but 5-year overall survival rates can exceed 70% for localized disease. There is a lack of standardized protocols for treatment and further research should be done to characterize this condition and optimize treatment strategies.