A rare and unusual presentation of Epstein-Barr virus-associated diffuse large B-cell lymphoma involving colon as the primary site.

Lymphoproliferative malignancies can involve both nodal- and extra-nodal tissues. The most common extranodal site involved is the gastrointestinal (GI) tract, and it is secondary to the widespread primary nodal disease. However, about 33% of non-Hodgkin's lymphoma primarily arise from tissues other than lymph nodes, spleen, or bone marrow, for example, GI tract, skin, or the central nervous system and are called primary extranodal lymphomas. The most common site of GI localization is stomach (50%-60%) followed by small bowel. Primary colonic lymphoma is seen only in 6% of GI lymphomas and up to 0.5%-1% of all colon malignancies. Hence, primary GI lymphoma is extremely rare, and primary colonic lymphoma is an even rarer occurrence. There is clearly a paucity of cases reported in literature resulting in unclear treatment protocol. Here, we report a case of a 51-year-old man who presented with abdominal pain, weight loss, and bright red blood per rectum. A colonoscopy revealed diffuse bleeding ulcers involving the entire colon. Pathology was consistent with primary diffuse large B-cell lymphoma arising from the colon. The patient was started on treatment with rituximab, cyclophosphamide, adriamycin, vincristine, and prednisone.