S3829 Primary Colonic B Cell Lymphoma

Introduction: Gastrointestinal (GI) tract lymphoma is the most common site for the development of extranodal lymphoma, given the significant presence of gut-associated lymphoid tissue. The colon and rectum are the rarest sites of a primary GI lymphoma. Symptoms may include abdominal pain, diarrhea, hematochezia, weight loss or fatigue, but some patients are asymptomatic. Diagnosis is obtained via histology, either from colonic biopsies or surgical resection specimens. Prognosis varies based on histologic subtype, with diffuse large B cell lymphoma (DLBCL) being the most common subtype, accounting for about 40%-50% of colorectal lymphomas. Case Description/Methods: Here we present a case of a 64-year-old man who presented for evaluation for chronic constipation and intermittent hematochezia. Colonoscopy showed a showed a large, friable, malignant-appearing mass at the hepatic flexure. Initial biopsies showed focal acute colitis with crypt abscesses, focal hyperplastic epithelial change, and mixed T and B cell lymphoid aggregates, negative for dysplasia and carcinoma. He underwent a positron emission tomography (PET) scan that showed radiotracer avidity at the hepatic flexure. Repeat biopsies then demonstrated Epstein-Barr virus-positive diffuse large B cell lymphoma (DLBCL). He was referred to oncology and started on R-CHOP for treatment. Repeat PET scan showed resolution of the colonic radiotracer uptake. Discussion: Colonic lymphoma is a rare entity, with DLBCL being the most common histologic subtype. DLBCL is rapidly proliferating and very responsive to multimodal chemotherapy. Staging can be done with imaging and bone marrow biopsy to evaluate for systemic involvement. Local disease may even be amenable to surgical resection.