ABSTRACT
Acute lymphoblastic leukemia is a cancer of blood cells. It is known as lymphoblastic lymphoma when it involves lymph nodes rather than the blood and bone marrow. The gastrointestinal tract is a predominant site for extra-nodal lymphomas. But, B-lymphoblastic leukemia/lymphoma more frequently presents in the leukemic form than in the lymphomatous form. We herein report a case of B-lymphoblastic leukemia/lymphoma detected as a laterally spreading tumor in the colon. A 54-year-old man was referred to our hospital for removal of multiple colonic polyps. A colonoscopy revealed multiple colonic polyps and several colonic laterally spreading tumors. An esophagogastroduodenoscopy revealed several raised erosive lesions on the fundus and several variable sized sessile polypoid lesions on the duodenum. We diagnosed B-lymphoblastic leukemia/lymphoma following biopsies of the lesions.