S4061 Gastrointestinal Involvement in Distinct B-Cell Lymphomas: A Comparative Case Report of EBV-Positive Diffuse Large B-Cell Lymphoma and Small Lymphocytic Leukemia

Introduction: While gastrointestinal (GI) tract involvement is well-described in certain lymphomas, it remains an uncommon but clinically significant finding in cases of Epstein-Barr virus-positive diffuse large B-cell lymphoma (EBV+ DLBCL), and small lymphocytic lymphoma (SLL). We report 2 cases of histologically distinct B-cell lymphomas with GI tract involvement to highlight the diagnostic and therapeutic implications in gastroenterology and oncology, with an associated literature review to evaluate the etiology, prognosis, and treatment of these rare, but potentially serious manifestations of lymphoma. Case Description/Methods: Patient 1 is a 66-year-old woman with a history of ischemic colitis who presented for routine screening colonoscopy. A 3 mm sessile polyp in the ascending colon and 2 2-3 mm polyps in the recto-sigmoid colon were isolated. Biopsies revealed EBV+ DLBCL confirmed via positive EBER and Ki-67 with proliferation index of ∼50%. Histopathology demonstrated large atypical lymphoid cells (CD45+), and immunophenotyping was consistent with a non-germinal center B-cell phenotype. The patient was initiated on R-CHOP chemotherapy for 21 days with repeat surveillance colonoscopy in 3-5 years. Patient 2 is a 61-year-old man who was diagnosed with small lymphocytic lymphoma (SLL) after surveillance colonoscopy identified abnormal mucosal nodularity including sessile polyps in the transverse and descending colon. Biopsies of these regions revealed lymphoid aggregates with a Ki-67 index of 10%–20%. Evaluation of pathology confirmed SLL exclusive to the GI tract (a rare manifestation). Further discussion with oncology determined therapeutic interventions were not warranted at this time. Instead, the patient continued outpatient monitoring with repeat surveillance colonoscopy every 3 years. Discussion: These cases underscore the relevance of colonoscopic findings in lymphomas with differing immunological presentations. EBV+ DLBCL is a rare, aggressive entity often presenting with extranodal disease, particularly in older or immunocompromised individuals. In contrast, SLL with exclusive GI involvement is less common and suggests a more indolent course that can be monitored as an outpatient but does not necessitate immediate treatment unlike DLCBL. Accurate immunophenotyping is critical for diagnosis, and recognition of GI involvement can impact staging and therapy. For gastroenterologists, awareness of these presentations is essential for timely diagnosis and coordination of multidisciplinary care.